Battery equalization control method
By collecting the open-circuit voltage of the battery cells to obtain the SOC and SOH, and using a passive balancing method, the problem of poor battery consistency was solved, extending battery life and improving driving range and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-31
- Publication Date
- 2026-03-10
AI Technical Summary
In existing technologies, poor cell consistency in vehicle batteries leads to short battery life, insufficient driving range, and inadequate safety, and the equalization control scenarios are limited and complex.
By collecting the open-circuit voltage of each cell, the State of Charge (SOC) and State of Health (SOH) are obtained. Using a passive balancing method, battery consistency is restored based on the differences in cell charge and health, thereby extending battery life and increasing driving range.
This improved the consistency of cells within the battery pack, extended battery life, and enhanced vehicle range and battery safety.
Smart Images
Figure CN121643155A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of vehicle battery, in particular to a battery equalization control method. BACKGROUND
[0002] With the rapid development of new energy vehicles, the market share has gradually increased. As an important component of new energy batteries, the consistency of the battery affects the driving range and acceleration experience of the vehicle. In the case that the internal resistance of the battery is almost the same and the capacity is consistent, according to the principle of the wooden bucket effect, the better the consistency of the battery, the more the amount of electricity that can be charged, the more the capacity that can be used by the vehicle, the wider the interval of the battery that can output large current, and the better the user experience.
[0003] The prior art vehicle calculates the SOC of each battery cell, identifies the highest and lowest SOC, and balances the highest and lowest battery cells through an inductive device and a wire harness through active balancing, or balances the battery pack at the end of discharge. The application scenario is limited, and the specific conditions for determining whether the battery cell needs to start balancing are more and complex. SUMMARY
[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to provide a battery equalization control method, which has the advantages of prolonging the service life of the battery, improving the driving range of the vehicle, and improving the safety of the battery.
[0005] The battery equalization control method according to an embodiment of the present application comprises: collecting the voltage of each battery cell to obtain an open circuit voltage; obtaining a correspondence between the open circuit voltage and the SOC, and obtaining the SOC of each battery cell according to the open circuit voltage of each battery cell; obtaining the SOH of each battery cell according to the correspondence between the open circuit voltage and the SOC and the cumulative capacity; and balancing the capacity of the corresponding battery cell according to the SOC and the SOH of each battery cell.
[0006] The battery equalization control method according to an embodiment of the present application has the advantages of prolonging the service life of the battery, improving the driving range of the vehicle, and improving the safety of the battery.
[0007] According to some specific embodiments of the present application, the SOH of each battery cell is obtained by: monitoring the SOC in real time to obtain the SOC at the current time e ; first obtaining the SOC of each battery cell under the open circuit voltage o1 ; and secondly obtaining the SOC of each battery cell under the open circuit voltage o2a percentage of electric quantity SOC of the first group of battery cells o1 a percentage of electric quantity SOC of the second group of battery cells under open circuit voltage o2 a percentage of electric quantity SOC of the current time e a battery health SOH value of each battery cell is calculated.
[0008] Further, the battery health SOH value of each battery cell satisfies: SOH= (SOC e -SOC o1 ) / (SOC o2 -SOC o1 ).
[0009] According to some embodiments of the present application, the balancing of the electric quantity of each battery cell according to the percentage of electric quantity SOC and the battery health SOH includes: selecting a battery cell that needs to be balanced, and determining a balancing capacity according to the battery health SOH of the battery cell; obtaining a current percentage of electric quantity SOC of the battery cell that needs to be balanced; and calculating a balancing time according to the balancing capacity AH and the current percentage of electric quantity SOC of the battery cell that needs to be balanced.
[0010] Further, the battery cell that needs to be balanced is the battery cell with the lowest battery health SOH.
[0011] According to some embodiments of the present application, the balancing time satisfies: T=[(SOC n -50%)×SOH n -(SOC L -50%)*SOH L ]×AH / I b ; wherein, T is the balancing time, SOC n is the SOC of the battery cell that needs to be balanced, SOH n is the battery health SOH corresponding to the n-th single cell, SOH L is the lowest battery health SOH value among all battery cells. SOC L is the SOC corresponding to the lowest battery health SOH value among all battery cells in the battery pack, AH is the rated capacity of the battery cell, and I b is the balancing current.
[0012] According to some embodiments of the present application, before the balancing time is calculated, the method further includes: calculating an electric quantity consumed by the balancing of the battery cell; and correcting the percentage of electric quantity SOC of the battery cell that needs to be balanced according to the electric quantity consumed by the balancing of the battery cell.
[0013] Further, the calculation of the electric quantity consumed by the balancing satisfies: wherein, . is the integral of the balancing current between the time t-1 of the n-th monomer t-1 to the time t, denoted as .
[0014] According to some embodiments of the present application, the battery health SOH of the lowest cell triggers the cut-off voltage condition, and the percentage of charge SOC of all cells needs to be synchronized to 50%; when the percentage of charge SOC of the battery health SOH of the lowest cell reaches 100%, the percentage of charge SOC of other cells is lower than 100%; when the percentage of charge SOC of the battery health SOH of the lowest cell reaches 0%, the percentage of charge SOC of other cells is higher than 0%.
[0015] According to some embodiments of the present application, the cell with the lowest battery health SOH triggers the charging cut-off and the discharging cut-off.
[0016] Additional aspects and advantages of the present application will be given in part in the following description, become apparent from the following description, or be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0017] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which: Figure 1 is a flow chart of a battery balancing control method according to an embodiment of the present application. DETAILED DESCRIPTION
[0018] The battery balancing control method according to an embodiment of the present application is described below with reference to the accompanying drawings.
[0019] As shown in Figure 1 , an embodiment according to the present application proposes a battery balancing control method, comprising: collecting the voltage of each cell to obtain the open circuit voltage; obtaining the correspondence between the open circuit voltage and the percentage of charge SOC, and obtaining the percentage of charge SOC of each cell according to the open circuit voltage of each cell; obtaining the battery health SOH of each cell according to the correspondence between the open circuit voltage and the percentage of charge SOC and the cumulative charge; balancing the charge of the corresponding cell according to the percentage of charge SOC and the battery health SOH of each cell.
[0020] For example, by collecting the voltage of each battery cell, the open circuit voltage of the battery cell is obtained at the first wake-up, and a correspondence table of the open circuit voltage of the battery cell and the percentage of the electric quantity SOC is obtained. The correspondence table of the open circuit voltage of the battery cell and the percentage of the electric quantity SOC can be obtained by a plurality of charging and discharging tests. The open circuit voltage of each battery cell is collected, and the percentage of the electric quantity SOC of the corresponding battery cell can be obtained.
[0021] The percentage of the electric quantity SOC is easy to understand, which represents the percentage of the remaining electric quantity. The battery health SOH represents how much performance is left of the battery compared to a new battery. For example, the battery health SOH of a brand-new battery is 100%, and after being used for a period of time, the battery health SOH is 80%, the battery has aged, and the capacity or power is only 80% of the original. The electric quantity of the corresponding battery cell is balanced, and the battery is started in the balancing mode.
[0022] According to the battery balancing control method of the embodiment of the present application, the percentage of the electric quantity SOC of each battery cell is calculated, the passive balancing function is used according to the difference in the percentage of the electric quantity SOC of the battery cell, and the consistency of the battery is realized. The existing capacity in the battery cell is calculated, and the battery voltage of all battery cells reaches the cut-off voltage at the moment when the battery is fully charged according to the AH integral calculation algorithm, the OCV algorithm, and other algorithms.
[0023] By using the battery balancing control method of the embodiment of the present application, the problem of poor consistency of the battery cells in the battery pack is solved by passive balancing control. When the battery voltage consistency is poor, the balancing function effectively improves the consistency of the battery voltage, prolongs the service life of the battery, improves the driving range of the vehicle, and improves the safety of the battery.
[0024] Therefore, according to the battery balancing control method of the embodiment of the present application, the service life of the battery is prolonged, the driving range of the vehicle is improved, and the safety of the battery is improved.
[0025] In some specific embodiments of the present application, the battery health SOH of each battery cell is obtained, including: The percentage of the electric quantity SOC at the current time is obtained by real-time monitoring e ; The percentage of the electric quantity SOC under the open circuit voltage of each battery cell is obtained for the first time o1 ; The percentage of the electric quantity SOC under the open circuit voltage of each battery cell is obtained for the second timeo2 ; According to the percentage of the electric quantity SOC of the first group of battery cells o1 and the percentage of the electric quantity SOC under the open circuit voltage of the second group of battery cells o2 and the percentage of the electric quantity SOC at the current time e The battery health SOH value of each battery cell can be calculated.
[0026] Wherein, the percentage of the electric quantity SOC of each battery cell is obtained by real-time monitoring and table lookup, and is denoted as SOC o1 When the open circuit voltage is obtained again, the percentage of the electric quantity SOC of each battery cell in the second group is obtained, and is denoted as SOC o2 The percentage of the electric quantity SOC at the current time can be obtained by real-time monitoring through AH integration, and is denoted as SOC At this time, the percentage of the electric quantity SOC will have a slight error due to the voltage collection accuracy, and is denoted as ΔU c The actual percentage of the electric quantity SOC of the battery cell can deviate slightly from the calculation, and according to the corresponding relationship table of the open circuit voltage and the percentage of the electric quantity SOC, the maximum percentage of the electric quantity SOC error at different temperatures can be obtained, and is denoted as ΔSOCd. In some specific embodiments of the present application, the battery health SOH value of each battery cell satisfies: SOH = (SOC e -SOC o1 ) / (SOC o2 -SOC o1 ).
[0027] That is, according to the percentage of the electric quantity SOC obtained by twice table lookup of the open circuit voltage and the percentage of the electric quantity SOC obtained by integration, the battery health SOH value of each battery cell can be calculated, and the calculation formula of the battery health SOH value of different battery cells is: SOH n = (SOC ne -SOC no1 ) / (SOC no2 -SOC no1 ) (Formula 1) Wherein, n in the formula represents the nth battery cell.
[0028] In some specific embodiments of the present application, balancing the electric quantity of the battery cells according to the percentage of the electric quantity SOC and the battery health SOH of each battery cell includes: Selecting the battery cells that need to be balanced, and determining the balancing capacity according to the battery health SOH of the battery cells; Obtaining the current percentage of the electric quantity SOC of the battery cells that need to be balanced; According to the balanced capacity AH and the current percentage SOC of the battery cell needing balancing, the time needing balancing is calculated.
[0029] Further, the battery cell needing balancing is the battery cell with the lowest SOH. Since the battery cell with the lowest SOH is taken as the reference point of balancing, it is necessary to ensure that the battery cell with the lowest SOH has the percentage SOC of other battery cells ≥ 50% when the percentage SOC of the battery cell with the lowest SOH reaches 50%, otherwise the battery cell with the lowest SOH needs to be balanced first.
[0030] In some embodiments of the present application, the balancing time satisfies: T=[(SOC n -50%)×SOH n -(SOC L -50%)×SOH L ]×AH / I b ; (Formula 2) Wherein, T is the time needing balancing, SOC n is the percentage SOC of the battery cell needing balancing, SOH n is the SOH corresponding to the n-th battery cell, SOH L is the lowest SOH value among all battery cells. SOC L is the percentage SOC corresponding to the lowest SOH value among all battery cells in the battery pack, AH is the rated capacity of the battery cell, and Ib is the balancing current.
[0031] When the battery cell is not started to balance, the change of the percentage SOC of the n-th battery cell in a period of time is estimated as follows: (Formula 3) is the integral of the current between t-1 and t, denoted as the change of the percentage SOC of the n-th battery cell in a period of time, denoted as .
[0032] Further, is the percentage SOC value of the n-th battery cell at t, and the calculation method is as follows: (Formula 4) Wherein, SOC n (t) is the percentage SOC value of the n-th battery cell at t, SOC n (t-1) is the percentage SOC value of the n-th battery cell at t-1, and △SOC nis the change of the percentage of the electric quantity SOC between the time t-1 and the time t of the n-th monomer.
[0033] In some embodiments of the present application, before calculating the time requiring balancing, further comprising: calculating the electric quantity consumed by the cell balancing; correcting the percentage of the electric quantity SOC of the cell requiring balancing according to the electric quantity consumed by the cell balancing.
[0034] Further, the calculation of the electric quantity consumed by the balancing satisfies: .
[0035] wherein I b is the balancing current, is the integral of the balancing current between the time t-1 and the time t of the n-th monomer, denoted as . That is, when the cell starts balancing, the cell balancing will also consume electric quantity, and the percentage of the electric quantity consumed by the balancing is calculated according to the following formula: (Formula 5) The real-time percentage of the electric quantity SOC of the balanced cell is calculated according to the following formula: (Formula 6) The balancing current can be calculated according to the selection of the resistance, and the formula is as follows: I b = U n (t) / R (Formula 7) wherein U n (t) is the voltage of the balanced cell, and R is the parallel balancing resistance value.
[0036] Since the monomer with the lowest battery health SOH is used as the reference point for balancing, it is necessary to ensure that the percentage of the electric quantity SOC of the monomer with the lowest battery health SOH reaches 50% when the percentage of the electric quantity SOC of the other cells is greater than or equal to 50%, otherwise the cell with the lowest battery health SOH needs to be balanced first.
[0037] According to the percentage of the electric quantity SOC and the battery health SOH, the electric quantity AH nd AH nd = (SOC n - 50%) x SOH n× AH (Formula 8) Then, according to the calculated AH nd , the maximum value AH is screened out, T L = AH nd / I b (Formula 9) wherein T L is the time needed for the lowest battery state of health SOH to be balanced.
[0038] The real-time percentage of charge SOC value of the battery cell can be obtained by the above formula, and then the excess charge can be released by means of parallel resistance according to the passive balancing needs.
[0039] In some embodiments of the application, the percentage of charge SOC of the battery cell with the lowest state of health SOH triggers the cutoff voltage condition, and the percentage of charge SOC of all battery cells needs to be synchronized to 50%. When the percentage of charge SOC of the battery cell with the lowest state of health SOH reaches 100%, the percentage of charge SOC of other battery cells is lower than 100%. When the percentage of charge SOC of the battery cell with the lowest state of health SOH reaches 0%, the percentage of charge SOC of other battery cells is higher than 0%.
[0040] In some embodiments of the application, the battery cell with the lowest state of health SOH triggers the charging cutoff and discharging cutoff.
[0041] Specifically, when the state of health SOH of different battery cells is inconsistent, the battery cell with the lowest state of health SOH should trigger the charging cutoff and discharging cutoff to release the maximum amount of electricity, that is, the lowest single cell voltage number during discharging and the highest single cell voltage number during charging are the same battery cell, so as to ensure that the battery releases electricity according to its maximum capacity.
[0042] To ensure that the battery cell with the lowest state of health SOH triggers the cutoff voltage condition during battery discharging and charging cutoff, the state of health SOC of all battery cells needs to be synchronized to 50%, the percentage of charge SOC of the battery cell with the lowest state of health SOH reaches 100% when the percentage of charge SOC of other battery cells is lower than 100%, and the percentage of charge SOC of the battery cell with the lowest state of health SOH reaches 0% when the percentage of charge SOC of other battery cells is higher than 0%.
[0043] In addition, while the battery balancing mode is turned on, the state of the balancing circuit needs to be monitored in real time to always remain in a normal state, and the battery balancing mode is turned off when the balancing circuit is in an abnormal state.
[0044] The battery and operation according to the embodiments of the application are known to those skilled in the art, and will not be described in detail here.
[0045] In the description of the specification, reference to "one embodiment", "some embodiments", "an exemplary embodiment", "an example", "a specific example", or "some examples" means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "in an exemplary embodiment", "an example", "a specific example", or "some examples" in various places in the specification are not necessarily referring to the same embodiment or example.
[0046] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. Rather, it is the intention that modifications, changes, substitutions, and variations be made to the embodiments disclosed herein without departing from the spirit and scope of the application, which is defined solely by the claims and their equivalents.
Claims
1. A battery equalization control method characterized by, The method comprises: collecting the voltage of each battery cell to obtain an open circuit voltage; obtaining a correspondence between the open circuit voltage and the state of charge (SOC) of each battery cell, and obtaining the state of charge (SOC) of each battery cell according to the open circuit voltage of each battery cell; obtaining the state of health (SOH) of each battery cell according to the correspondence between the open circuit voltage and the state of charge (SOC) and the cumulative charge; equalizing the charge of each battery cell according to the state of charge (SOC) and the state of health (SOH) of each battery cell.
2. The battery equalization control method according to claim 1, characterized by, The method for obtaining the state of health (SOH) of each battery cell comprises: Real-time monitoring gets the current time of the power percentage SOC e ; The first time to obtain the percentage of electric quantity of each battery cell at open circuit voltage SOC o1 ; Secondly, the percentage of electric quantity SOC under open circuit voltage of each battery cell is acquired o2 ; a state of charge (SOC) percentage of the first group of battery cells o1、 a state of charge (SOC) percentage of the second group of battery cells at open circuit voltage o2 a state of charge (SOC) percentage at a current time e a battery state of health (SOH) value for each battery cell 3. The battery equalization control method according to claim 2, characterized by, The battery health SOH value of each battery cell satisfies: SOH = (SOC e -SOC o1 ) / (SOC o2 -SOC o1 ).
4. The battery equalization control method according to claim 1, characterized by, The method for equalizing the charge of each battery cell according to the state of charge (SOC) and the state of health (SOH) of each battery cell comprises: selecting a battery cell that needs to be equalized, and determining the equalization capacity according to the state of health (SOH) of the battery cell; obtaining the current state of charge (SOC) of the battery cell that needs to be equalized; calculating the equalization time according to the equalization capacity (AH) and the current state of charge (SOC) of the battery cell that needs to be equalized.
5. The battery equalization control method according to claim 4, characterized by, The battery cell that needs to be equalized is the battery cell with the lowest state of health (SOH).
6. The battery equalization control method according to claim 4, characterized by, The equalization time satisfies: T=[(SOC n -50%)×SOH n -(SOC L -50%)*SOH L ]×AH / I b ; wherein T is the time needed for balancing, SOC n is the SOC of the battery cell that needs balancing, SOH n is the battery health SOH of the n-th cell, SOH L is the lowest battery health SOH value of all battery cells. SOC L is the SOC corresponding to the lowest battery health SOH value of all battery cells in the battery pack, AH is the rated capacity of the battery cell, I b is the balancing current.
7. The battery equalization control method according to claim 4, characterized by, Before calculating the equalization time, the method further comprises: calculating the charge consumed by the equalization of the battery cell; correcting the state of charge (SOC) of the battery cell that needs to be equalized according to the charge consumed by the equalization of the battery cell.
8. The cell equalization control method according to claim 7, wherein The calculated equalized consumed power satisfies: . where I b is the equalization current. is the integral of the equalization current between time t-1 and time t for the n-th cell, denoted by .
9. The battery equalization control method according to claim 1, wherein all the battery cells with the lowest state of health (SOH) trigger the cut-off voltage condition, and the state of charge (SOC) of all the battery cells needs to be synchronized to 50%; when the state of charge (SOC) of the battery cell with the lowest state of health (SOH) reaches 100%, the state of charge (SOC) of the battery of other battery cells is lower than 100%; when the state of charge (SOC) of the battery cell with the lowest state of health (SOH) reaches 0%, the state of charge (SOC) of the battery of other battery cells is higher than 0%.
10. The battery equalization control method according to claim 1, characterized by, The battery cell with the lowest state of health (SOH) triggers the charging cut-off and the discharging cut-off.