Full-time equalization control method based on lithium ion battery real-time voltage difference estimation

Abstract

The invention relates to the technical field of battery equalization, in particular to a full-time equalization control method based on lithium ion battery real-time voltage difference estimation, which comprises the following steps of: setting an equalization trigger condition by combining full power end time, bus current, temperature of single batteries and voltage difference between the single batteries; after the equalization triggering condition is met, an equalization mode is selected, equalization is started according to an equalization duty ratio corresponding to the selected equalization mode, and the equalization duty ratio is controllably adjusted in the equalization process; and calculating the average voltage of the single batteries after the equalization is started, estimating the equalization target voltage in real time through the average voltage, and selecting the equalization target voltage for equalization. According to the method, the purpose of full-time equalization is achieved by estimating the static and dynamic voltage differences between the lithium ion batteries in real time, so that the problem that charging tail end equalization, discharging tail end equalization or static equalization cannot be balanced under the dynamic working condition is solved, and the equalization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery balancing, and in particular to a full-time balancing control method. Background Art

[0002] At present, the voltage differential balancing based on lithium-ion batteries in the market mainly includes static state balancing or full-time balancing based on power estimation. Its purpose is to reduce the voltage differential between lithium-ion batteries through balancing, thereby increasing the charge and discharge depth of the battery. The static state balancing is further divided into charging end balancing, discharging end balancing or small current state balancing at the non-charging and discharging end. Static balancing can only balance lithium-ion batteries in a static state, and cannot achieve balancing in dynamic mode. The balancing efficiency is low. Although full-time balancing based on power estimation can achieve balancing in static and dynamic conditions, due to the accuracy of power estimation, it often causes lithium-ion batteries to be over-balanced and cannot accurately achieve the balancing effect. The low efficiency of static balancing and the poor accuracy of full-time balancing based on power estimation make the balancing effect on the voltage differential balancing of lithium-ion batteries not good in actual use, and cannot effectively reduce the voltage differential between lithium-ion batteries. Summary of the invention

[0003] The purpose of the present invention is to provide a full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries to solve the above technical problems;

[0004] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0005] A full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries, comprising:

[0006] Step S1, setting a balancing trigger condition in combination with the full-charge end time, bus current, temperature of the single cell and the voltage difference between the single cells;

[0007] Step S2, after the balancing trigger condition is met, selecting a balancing mode, starting balancing with a balancing duty cycle corresponding to the selected balancing mode, and controllably adjusting the balancing duty cycle during the balancing process;

[0008] Step S3, calculating the average voltage of the single battery after balancing is turned on, estimating the balancing target voltage in real time according to the average voltage, and selecting the balancing target voltage for balancing;

[0009] Step S4, setting a balance end condition, detecting the validity of the balance target voltage, and ending the balance when the balance target voltage is invalid and the balance end condition is met.

[0010] Preferably, the equalization triggering condition set in step S1 includes:

[0011] The full charge end time exceeds the first preset time threshold;

[0012] The bus current is within the preset current range;

[0013] The cell temperature extreme value of the single cell is within a preset temperature range;

[0014] The voltage difference between the highest cell voltage and the lowest cell voltage exceeds a preset voltage difference threshold.

[0015] Preferably, in step S2, the balancing mode includes a balancing full-on mode and a balancing non-full-on mode. The balancing full-on mode is to enable balancing for all the single cells at the same time; the balancing non-full-on mode is to enable balancing for the single cells at a preset duty cycle.

[0016] Preferably, in step S2, the control method for balancing the duty cycle includes:

[0017] Balancing the single cells with odd and even numbers alternately in groups in different unit time, balancing the single cells with odd numbers in one unit time, and balancing the single cells with even numbers in the next unit time; or;

[0018] The balancing duty cycle is directly adjusted, and the single cells are balanced according to the adjusted balancing duty cycle.

[0019] Preferably, step S3 also includes switching the balancing mode according to the change of the balancing temperature during the balancing process. If the balancing temperature is less than or equal to the first switching temperature threshold, balancing is performed in the balancing fully-open mode; if the balancing temperature is greater than the first switching temperature threshold, balancing is performed in the balancing non-full-open mode.

[0020] Preferably, step S3 further includes controllably pausing balancing during the balancing process, and the balancing suspension method includes, in the charging mode, if the charging completion flag is invalid, and the difference between the highest single cell voltage and the full-charge cut-off voltage is within the first suspension range, entering the charging end balancing suspension; otherwise, continuing the balancing.

[0021] Preferably, in step S3, the balancing pause method further comprises: in the discharge mode, if the discharge completion flag is invalid and the difference between the lowest cell voltage and the emptying cut-off voltage is within the second pause range, entering the discharge end balancing pause; otherwise, continuing the balancing.

[0022] Preferably, in step S3, the method for calculating the balanced target voltage includes:

[0023] Step S31, calculating the average voltage;

[0024] Step S32, comparing the cell voltages of the cell batteries with the average voltage respectively, and sorting the cell batteries according to the differences between the cell voltages and the average voltage;

[0025] Step S33, selecting N of the cell voltages that are closest to the average voltage as the equalization target voltage;

[0026] Wherein N is a positive integer.

[0027] Preferably, judging the validity of the balanced target voltage includes:

[0028] In the discharge mode, if the balanced target voltage is not greater than the second lowest cell voltage of the battery system, confirm that the balanced target voltage is invalid; otherwise, keep the balanced target voltage valid; or;

[0029] In the charging mode, if the balanced target voltage is not less than the second highest cell voltage of the battery system, it is confirmed that the balanced target voltage is invalid; otherwise, the balanced target voltage is kept valid.

[0030] Preferably, in step S4, the equilibrium is terminated when one of the equilibrium termination conditions is reached, and the equilibrium termination condition further includes:

[0031] When the full-charge end time is greater than or equal to a second preset time threshold and the charging current is less than or equal to a preset current threshold and the difference between the equalization target voltage and the average voltage is within a preset end voltage difference range, end the equalization;

[0032] When the balancing time exceeds the preset end time threshold, the balancing ends.

[0033] Beneficial effects of the present invention: Due to the adoption of the above technical scheme, the present invention achieves the purpose of full-time balancing by real-time estimation of the static and dynamic pressure differences between lithium-ion batteries, thereby solving the problem that charging end balancing, discharging end balancing or static balancing cannot be balanced under dynamic conditions, thereby improving the balancing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the steps of a full-time balancing control method based on real-time pressure difference estimation of lithium-ion batteries in an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of step S3 in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0039] A full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries, such as Figure 1 As shown, including

[0040] Step S1, setting a balancing trigger condition in combination with the full-charge end time, bus current, single cell temperature and voltage difference between single cells;

[0041] Step S2, after the balancing trigger condition is met, the balancing mode is selected, the balancing is started with the balancing duty cycle corresponding to the selected balancing mode, and the balancing duty cycle is controllably adjusted during the balancing process;

[0042] Step S3, after balancing is started, the average voltage of the single cells is calculated, the balancing target voltage is estimated in real time through the average voltage, and the balancing target voltage is selected for balancing;

[0043] Step S4, setting the equalization end condition, detecting the validity of the equalization target voltage, and ending the equalization when the equalization target voltage is invalid and the equalization end condition is met.

[0044] Specifically, the present invention aims to achieve full-time balancing by real-time estimation of static and dynamic pressure differences between lithium-ion batteries, thereby solving the problem that charging end balancing, discharging end balancing or static balancing cannot be balanced under dynamic conditions, thereby improving balancing efficiency.

[0045] The present invention aims to achieve the purpose of full-time balancing by real-time estimation of the static and dynamic pressure differences between lithium-ion batteries, thereby solving the accuracy problems, chip operation speed problems and development cycle problems of full-time balancing based on power estimation, thereby improving the balancing effect, reducing chip computing power and shortening the development cycle.

[0046] Compared with the charging end equalization, discharging end equalization or static equalization in the prior art, the present invention has higher equalization efficiency. Charging end equalization, discharging end equalization or static equalization can only be performed under static conditions and specific working conditions, while the full-time equalization scheme based on real-time pressure difference estimation of lithium-ion batteries can be performed under both dynamic and static conditions, thereby effectively improving the equalization efficiency.

[0047] In a preferred embodiment, the equalization triggering condition set in step S1 includes:

[0048] The full charge end time exceeds the first preset time threshold;

[0049] The bus current is within the preset current range;

[0050] The cell temperature extreme value of the single battery is within the preset temperature range;

[0051] The voltage difference between the highest cell voltage and the lowest cell voltage exceeds a preset voltage difference threshold.

[0052] Specifically, the process of the present invention includes six parts: equalization triggering condition, equalization mode judgment, equalization mode conversion, equalization suspension, equalization reference voltage estimation and equalization end.

[0053] The balancing triggering conditions refer to the conditions that must be met for the lithium-ion battery balancing to start, including the full charge end time, bus current, temperature range, and voltage difference between lithium-ion batteries;

[0054] The full charge end time refers to the duration from when the controller determines that the charging completion flag is valid to when there is no charging current and the discharge current is not greater than a preset current threshold, which exceeds the first preset time threshold. At this time, the lithium-ion battery is fully charged, and the natural discharge current is also very small to meet the balancing requirement;

[0055] The bus current refers to the charge and discharge current of the lithium-ion battery. When the bus current is within the preset current range, the charge and discharge current of the lithium-ion battery is very small, and the voltage is stable, which can meet the balance requirements.

[0056] The cell temperature extreme value of a single cell is within a preset temperature range, which means that in a lithium-ion battery, the maximum temperature of the single cell and the minimum temperature of the single cell are within the preset temperature range. The preset temperature range here is the temperature extreme value range, which can be represented by the interval [TEMPmax, TEMPmin], and refers to the upper limit of the maximum temperature and the lower limit of the minimum temperature in which the capacity difference of the lithium-ion battery is P%.

[0057] The voltage difference between the highest single cell voltage and the lowest single cell voltage exceeds the preset voltage difference threshold value, which means that the voltage difference between lithium-ion batteries needs to exceed the preset voltage difference threshold value. The preset voltage difference threshold value here is the minimum condition for turning on balancing, which is usually above 40mv. The purpose of balancing is to balance the voltage difference between single cells. If the voltage difference between ion batteries is already very low, there is no need to turn on balancing. Usually, the voltage difference condition that needs to be met to turn on balancing is preferably between 40mv and 60mv.

[0058] In a preferred embodiment, in step S2, the balancing mode includes a balancing full-on mode and a balancing non-full-on mode. The balancing full-on mode is to enable balancing for all single cells at the same time; the balancing non-full-on mode is to enable balancing for single cells at a preset duty cycle.

[0059] Specifically, the balancing mode refers to the balancing method used to ensure balancing safety to prevent damage to the balancing hardware due to excessive temperature, including balancing full-on mode and balancing non-full-on mode. The balancing full-on mode means that the balancing duty cycle is 100% and the balancing of the balanced lithium-ion batteries is all turned on at the same time. The balancing non-full-on mode means that the balancing duty cycle is less than 100% and greater than 0 or the balanced lithium-ion batteries are not all turned on at the same time.

[0060] In a preferred embodiment, in step S2, the control method for balancing the duty cycle includes:

[0061] Balancing the single cells with odd and even numbers in groups alternately in different unit time, balancing the single cells with odd numbers in one unit time, and balancing the single cells with even numbers in the next unit time; or;

[0062] The balancing duty cycle is directly adjusted, and the single cells are balanced according to the adjusted balancing duty cycle.

[0063] In a preferred embodiment, step S3 also includes switching the balancing mode according to the change of the balancing temperature during the balancing process. If the balancing temperature is less than or equal to the first switching temperature threshold, balancing is performed in the balancing fully open mode; if the balancing temperature is greater than the first switching temperature threshold, balancing is performed in the balancing non-full open mode.

[0064] Specifically, the balancing mode conversion refers to the mode switching according to the change of the balancing temperature during the lithium-ion battery balancing process. When the temperature is not greater than the first switching temperature threshold, the balancing full-open mode is entered; when the temperature is greater than the first switching temperature threshold, the balancing non-full-open mode is entered.

[0065] The balancing non-full-open mode will further adjust the balancing duty cycle according to the balancing temperature. When the temperature is not greater than the second switching temperature threshold, balancing is performed with a duty cycle of 80% to 90%, for example, that is, 80% to 90% of the single cells are balanced. When the balancing temperature is greater than the second switching temperature threshold, balancing is performed with the minimum duty cycle. The second switching temperature threshold is the upper limit of the balancing temperature, for example, 80°C. When the temperature is too high, the non-full-open mode corresponding to the lowest temperature rise is turned on. For example, the non-full-open balancing mode that alternately balances single cells with odd and even numbers in different unit time groups is the non-full-open mode with the lowest temperature rise. When the balancing temperature exceeds 80°C, balancing is performed by alternately balancing single cells with odd and even numbers in different unit time groups.

[0066] The equilibrium temperature in the present invention is the temperature of the circuit board integrated with the lithium-ion battery. The circuit board is provided with a temperature sampling module, and the temperature of each single cell in the lithium-ion battery and the temperature of the circuit board are detected by the temperature sampling module.

[0067] In a preferred embodiment, step S3 also includes controllably pausing balancing during the balancing process, and the balancing suspension method includes, in the charging mode, if the charging completion flag is invalid, and the difference between the highest single cell voltage and the full-charge cut-off voltage is within the first suspension range, entering the charging end balancing suspension; otherwise, continuing the balancing.

[0068] In a preferred embodiment, in step S3, the balancing pause method further includes, in the discharge mode, if the discharge completion flag is invalid and the difference between the lowest cell voltage and the emptying cut-off voltage is within the second pause range, entering the discharge end balancing pause; otherwise, continuing the balancing.

[0069] Specifically, the balancing pause refers to the lithium-ion battery entering a balancing pause when the balancing target needs to be re-evaluated due to changes in conditions during the balancing process. The balancing pause of the present invention includes temperature out-of-range balancing pause, charging end balancing pause and discharging end balancing pause.

[0070] When the temperature exceeds the range, the balancing will be suspended. When the temperature of the battery cell exceeds the preset temperature range, the balancing will be suspended. When the temperature of the battery cell is within the preset temperature range, the balancing will continue.

[0071] The end-of-charge equalization pause means that in the charging mode, the charging completion flag is invalid and the highest single-cell voltage of the lithium-ion battery is greater than the full-charge voltage of the lithium-ion battery minus a voltage value. The equalization is paused. The voltage value here is as small as possible, indicating that the highest single-cell voltage is close to the full-charge cut-off voltage;

[0072] If the charge completion flag is invalid and the controller exits the charge mode, balancing continues.

[0073] The end-of-discharge balance pause means that in the discharge mode, the discharge completion flag is invalid and the lowest single cell voltage of the lithium-ion battery is less than the lithium-ion battery empty voltage plus a voltage value. The voltage value here is as small as possible, indicating that the lowest single cell voltage is close to the empty cut-off voltage;

[0074] If the condition for suspending the balance at the end of discharge is not met, continue the balance.

[0075] In a preferred embodiment, Figure 2 As shown, in step S3, the method for calculating the balanced target voltage includes:

[0076] Step S31, calculating the average voltage;

[0077] Step S32, comparing the cell voltages of the single cells with the average voltage respectively, and sorting the single cells according to the difference between the cell voltages and the average voltage;

[0078] Step S33, selecting N cell voltages that are closest to the average voltage among the cell voltages as the equalization target voltage;

[0079] Wherein N is a positive integer.

[0080] Specifically, the equalization target voltage refers to the target voltage that the equalized lithium-ion battery voltage is to reach. The present invention adopts a full-time equalization solution, and the equalization reference voltage needs to be calculated in real time. After the equalization is triggered, the average voltage AVERAGE_CellU of the lithium-ion battery is calculated;

[0081] Then the balanced target voltage CellUxy is estimated from the average voltage AVERAGE_CellU;

[0082] In the present invention, the balanced target voltage needs to be as close to the average voltage as possible. The setting conditions of the present invention are:

[0083] |CellUx-AVERAGE_CellU|≤3mV

[0084] Where CellUx is the cell voltage;

[0085] The present invention takes the N values ​​closest to the average voltage in CellUx as the balanced target voltage CellUxy;

[0086] In this embodiment, N is 3 as an example, and the three values ​​closest to the average voltage in CellUx are taken as the equalization target voltages CellUxy, which are respectively recorded as CellUx0, CellUx1, and CellUx2. The three obtained equalization target voltages CellUxy are used as reference voltages for the equalization process.

[0087] Specifically, compared with full-time balancing based on power estimation, the present invention has better balancing accuracy. The purpose of balancing is to reduce the pressure difference between lithium ions. The present invention directly balances the lithium-ion battery from the perspective of pressure difference control, which not only reduces the calculation complexity, but also can effectively avoid problems such as over-balancing or under-balancing caused by full-time balancing based on power estimation.

[0088] Specifically, compared with end-of-charge balancing, end-of-discharge balancing, static balancing or full-time balancing based on power estimation, the present invention also adds a redundant design, and reduces the balancing stop caused by the failure of the reference voltage in the balancing process by adding multiple balancing target voltages. The present invention only adopts a design of 3 balancing reference voltages. In actual use, the number of balancing reference voltages can be revised according to project needs, so as to achieve the purpose of better balancing target voltage redundant design.

[0089] In a preferred embodiment, determining the validity of the balanced target voltage includes:

[0090] In the discharge mode, if the equalization target voltage is not greater than the second lowest cell voltage of the battery system, confirm that the equalization target voltage is invalid; otherwise, keep the equalization target voltage valid; or;

[0091] In the charging mode, if the equalization target voltage is not less than the second highest single cell voltage of the battery system, it is confirmed that the equalization target voltage is invalid; otherwise, the equalization target voltage is kept valid.

[0092] Specifically, the present invention ends the equalization by judging the validity of the equalization reference voltage. In the discharge mode, if the equalization target voltage CellUxy is not greater than the second lowest single cell voltage of the lithium ion battery system, the equalization target voltage is an invalid value. If the three equalization target voltages CellUx0, CellUx1, and CellUx2 are all invalid values, this equalization ends.

[0093] In a preferred embodiment, in step S4, the balancing is terminated when one of the balancing termination conditions is reached, and the balancing termination condition further includes:

[0094] When the full charge end time is greater than or equal to the second preset time threshold and the charging current is less than or equal to the preset current threshold and the difference between the equalization target voltage and the average voltage is within the preset end voltage difference range, end the equalization;

[0095] When the balancing time exceeds the preset end time threshold, the balancing ends.

[0096] Specifically, compared with charging end equalization, discharging end equalization, static equalization or full-time equalization based on power estimation, the present invention has higher reliability. The present invention adopts a real-time reference voltage estimation method, and can continuously correct the equalization target during the equalization process to ensure the timeliness of the equalization target. At the same time, the equalization target voltage is compared with the lowest single cell voltage of the lithium electronic battery system in real time. When the equalization target voltage is close to the lowest single cell voltage of the lithium ion battery system, the locking of the equalization target voltage is invalid and the equalization is stopped, thereby improving the reliability of the equalization process.

[0097] Specifically, the balancing end condition of the present invention also includes a full power end balancing condition and a balancing time end balancing condition;

[0098] The full-charge end balancing condition refers to ending balancing by judging the full-charge time. Regardless of whether the previous balancing is ended, if the full-charge end time is not less than the second preset time threshold and the charging current is not greater than the preset current threshold and the balancing target voltage minus the average voltage is not greater than the balancing target voltage difference minus a voltage value, balancing ends.

[0099] The balancing is ended by judging the balancing time. This means that the single balancing time continues to exceed the preset end time threshold, and the balancing is ended.

[0100] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries, characterized in that: include, Step S1, setting a balancing trigger condition in combination with the full-charge end time, bus current, temperature of the single cell and the voltage difference between the single cells; Step S2, after the balancing trigger condition is met, selecting a balancing mode, starting balancing with a balancing duty cycle corresponding to the selected balancing mode, and controllably adjusting the balancing duty cycle during the balancing process; Step S3, calculating the average voltage of the single battery after balancing is turned on, estimating the balancing target voltage in real time according to the average voltage, and selecting the balancing target voltage for balancing; Step S4, setting a balance end condition, detecting the validity of the balance target voltage, and ending the balance when the balance target voltage is invalid and the balance end condition is met.

2. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: The equalization triggering conditions set in step S1 include: The full charge end time exceeds the first preset time threshold; The bus current is within the preset current range; The cell temperature extreme value of the single cell is within a preset temperature range; The voltage difference between the highest cell voltage and the lowest cell voltage exceeds a preset voltage difference threshold.

3. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: In step S2, the balancing mode includes a balancing full-on mode and a balancing non-full-on mode. The balancing full-on mode is to enable balancing for all the single cells at the same time; the balancing non-full-on mode is to enable balancing for the single cells at a preset duty cycle.

4. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: In step S2, the control method for balancing the duty cycle includes: Balancing the single cells with odd and even numbers alternately in groups in different unit time, balancing the single cells with odd numbers in one unit time, and balancing the single cells with even numbers in the next unit time; or; The balancing duty cycle is directly adjusted, and the single cells are balanced according to the adjusted balancing duty cycle.

5. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 3 is characterized in that: Step S3 further includes switching the balancing mode according to the change of the balancing temperature during the balancing process, and if the balancing temperature is less than or equal to the first switching temperature threshold, balancing is performed in the balancing full-open mode; If the balancing temperature is greater than the first switching temperature threshold, balancing is performed in the balancing non-full-open mode.

6. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: Step S3 also includes controllably pausing balancing during the balancing process, wherein the balancing suspension method includes, in the charging mode, if the charging completion flag is invalid, and the difference between the highest single cell voltage and the full-charge cut-off voltage is within the first suspension range, entering the charging end balancing suspension; Otherwise, continue with balancing.

7. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: In step S3, the equalization suspension method further includes, in the discharge mode, if the discharge completion flag is invalid, and the difference between the lowest cell voltage and the emptying cut-off voltage is within the second suspension range, entering the discharge end equalization suspension; Otherwise, continue with balancing.

8. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: In step S3, the method for calculating the balanced target voltage includes: Step S31, calculating the average voltage; Step S32, comparing the cell voltages of the cell batteries with the average voltage respectively, and sorting the cell batteries according to the differences between the cell voltages and the average voltage; Step S33, selecting N of the cell voltages that are closest to the average voltage as the equalization target voltage; Wherein N is a positive integer.

9. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: Judging the validity of the balanced target voltage includes: In the discharge mode, if the equalization target voltage is not greater than the second lowest cell voltage of the battery system, confirming that the equalization target voltage is invalid; Otherwise, keeping the balanced target voltage valid; or; In the charging mode, if the balanced target voltage is not less than the second highest cell voltage of the battery system, it is confirmed that the balanced target voltage is invalid; otherwise, the balanced target voltage is kept valid.

10. The full-time equalization control method based on real-time pressure difference estimation of lithium-ion batteries according to claim 1, characterized in that: In step S4, the equilibrium is terminated when one of the equilibrium termination conditions is reached, and the equilibrium termination condition further includes: When the full-charge end time is greater than or equal to a second preset time threshold and the charging current is less than or equal to a preset current threshold and the difference between the equalization target voltage and the average voltage is within a preset end voltage difference range, end the equalization; When the balancing time exceeds the preset end time threshold, the balancing ends.

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