WO2024087386A1 - 电池组的电量均衡方法及系统、电池管理系统 - Google Patents

电池组的电量均衡方法及系统、电池管理系统 Download PDF

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Publication number
WO2024087386A1
WO2024087386A1 PCT/CN2022/144106 CN2022144106W WO2024087386A1 WO 2024087386 A1 WO2024087386 A1 WO 2024087386A1 CN 2022144106 W CN2022144106 W CN 2022144106W WO 2024087386 A1 WO2024087386 A1 WO 2024087386A1
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Prior art keywords
battery
voltage
balancing
battery pack
threshold voltage
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PCT/CN2022/144106
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English (en)
French (fr)
Inventor
彭宏伟
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湖北亿纬动力有限公司
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Publication of WO2024087386A1 publication Critical patent/WO2024087386A1/zh

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014—Circuits for equalisation of charge between batteries
    • H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014—Circuits for equalisation of charge between batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the embodiments of the present application relate to the field of power battery technology, for example, to a battery pack power balancing method and system, and a battery management system.
  • the batteries are usually screened before being assembled into battery packs.
  • the consistency of single cells is good, but as the battery pack is used for a long time, there will still be inconsistencies.
  • equalization adjustment is usually adopted, but in the related art, equalization is usually carried out under fixed operating conditions during the equalization process, and there are still deficiencies in the equalization control, which affects the consistency of the battery pack and the equalization effect.
  • the present application provides a battery pack power balancing method and system, and a battery management system, which increase the balancing flexibility, improve the consistency of the battery pack, and improve the available capacity and available energy of the battery pack.
  • an embodiment of the present application provides a battery pack power balancing method, including:
  • the target battery is charged and balanced.
  • an embodiment of the present application further provides a battery balancing control system for a battery pack, comprising:
  • An acquisition module configured to acquire the battery status of a single battery in the battery pack
  • a working condition determination module configured to determine a battery working condition of the single battery according to the battery state
  • a judgment module configured to judge whether the battery pack needs to be balanced according to the battery operating condition, and if it is judged that the battery pack needs to be balanced, determine a target battery in the battery pack that needs to be balanced according to the battery state and the battery operating condition;
  • the balancing module is configured to balance the power of the target battery.
  • an embodiment of the present application further provides a battery management system, including a battery balancing control system of a battery pack, wherein the battery balancing control system of the battery pack includes:
  • An acquisition module configured to acquire the battery status of a single battery in the battery pack
  • a working condition determination module configured to determine a battery working condition of the single battery according to the battery state
  • a judgment module configured to judge whether the battery pack needs to be balanced according to the battery operating condition, and if it is judged that the battery pack needs to be balanced, determine a target battery in the battery pack that needs to be balanced according to the battery state and the battery operating condition;
  • a balancing module configured to balance the power of the target battery
  • the battery management system includes: a secondary master control module, a voltage slave control module and a temperature acquisition slave board;
  • the working condition determination module and the judgment module are integrated in the secondary main control module
  • the acquisition module is integrated in the voltage slave control module and the temperature acquisition slave board
  • the balancing module is integrated in the voltage slave control module.
  • the technical solution provided in the embodiment of the present application determines the current battery operating condition of the battery pack through the battery status of the single cell, and performs balancing judgment on the battery pack according to different battery operating conditions. If the balancing requirements are met, the target battery to be balanced in the battery pack is determined according to the battery status and the battery operating condition, thereby performing power balancing on the target battery. The target battery is judged and selected based on the battery operating condition, thereby avoiding the conditional restrictions brought about by the balancing judgment under a single operating condition, improving the flexibility of power balancing, improving the consistency of the battery pack, and improving the available capacity and available energy of the battery pack.
  • FIG1 is a schematic flow chart of a method for balancing a battery pack according to an embodiment of the present application
  • FIG2 is a schematic diagram of a flow chart of cell equalization judgment of a battery pack under a charging end condition provided by an embodiment of the present application;
  • FIG3 is a schematic diagram of a process for determining a target battery to be balanced in a battery pack according to a battery state and a battery operating condition, provided in an embodiment of the present application;
  • FIG4 is a schematic diagram of a process for determining and selecting a target battery for battery balancing of a battery pack under a fully static working condition according to an embodiment of the present application
  • FIG5 is a schematic diagram of a process for determining and selecting a target battery for battery balancing of a battery pack under a fully static working condition, provided in an embodiment of the present application;
  • FIG6 is a schematic diagram of a flow chart of battery equalization judgment of a battery pack under charging conditions provided in an embodiment of the present application
  • FIG7 is a schematic diagram of the structure of a battery balancing control system for a battery pack provided in an embodiment of the present application.
  • FIG8 is a schematic diagram of the structure of a battery management system provided in an embodiment of the present application.
  • FIG9 is a schematic flow chart of a balancing control method provided in an embodiment of the present application.
  • FIG10 is a schematic diagram of a flow chart of a balance judgment provided in an embodiment of the present application.
  • FIG11 is a schematic diagram of a process for processing balance judgment according to an embodiment of the present application.
  • FIG12 is a schematic diagram of a circuit structure of a balancing module provided in an embodiment of the present application.
  • FIG. 13 is a schematic diagram of a balancing branch structure provided in an embodiment of the present application.
  • FIG1 is a flow chart of a battery pack power balancing method provided in an embodiment of the present application. This embodiment is applicable to battery balancing situations.
  • the method can be executed by a battery balancing control system, and the device can be implemented in hardware and/or software. The method includes the following steps:
  • the battery state refers to the operating state of a single cell, which is characterized by parameters such as the current, voltage, and temperature of the single cell.
  • the operating state of the single cell can be acquired through corresponding sensors, sensor chips, and other acquisition devices.
  • the battery pack has charging and resting processes in the application, so the operating conditions of the battery pack include at least one of the charging end condition, the fully resting condition and the charging condition.
  • the charging end condition refers to the state when the charging current reduction ends and the battery is fully charged.
  • the fully resting condition means that the battery current is less than the preset current for a preset time, and the battery can be considered to be fully resting, or the battery management system reads the system time after the low voltage is powered off and then powered on again. If the power-on time and the last power-off time exceed the preset time, the battery is also considered to be fully resting.
  • the charging condition includes the charging condition and the post-charging condition.
  • the charging condition refers to the single cell battery being able to maintain a charging current higher than the preset current for a certain period of time, for example, the single cell battery continuously has a charging current of more than 2A for 5 seconds.
  • the post-charging condition refers to the current in the preset interval from the charging condition or the charging end condition that continues for more than the preset time, that is, jumps to the charging end condition. For example, if the current within -2A to 10A continues for more than 1 minute, it jumps to the charging end condition. If there is a discharge current exceeding 10A, it jumps to the non-charging state.
  • the preset time and the corresponding voltage setting can be selected and set according to the battery type.
  • the degree of imbalance of the battery group under the corresponding operating conditions is judged. If equalization is required, the battery that needs to be balanced is determined and marked according to the current corresponding operating conditions and the battery current, voltage and other parameters, so as to obtain the target battery.
  • the balance is judged by taking the charging end condition as an example, and the first threshold voltage and the second threshold voltage are determined according to the battery performance.
  • the first threshold voltage VL1 is selected as 3.5V
  • the second threshold voltage VH is selected as 3.55V.
  • the voltage of all single cells is less than the first threshold voltage VL1, it means that the voltage of all single cells is low, and the battery does not need to be balanced at this time. If the voltage of all single cells is greater than the second threshold voltage VH, it means that the voltage of all single cells reaches the voltage target, and the battery does not need to be balanced at this time. If the voltage of some single cells is greater than the second threshold voltage VH and the voltage of some single cells is less than the first threshold voltage VL1, that is, the voltage of the battery is uneven, then the battery is unbalanced, which means that the single cell needs to be balanced.
  • the average voltage of the single battery is less than the first threshold voltage VL1, it means that there are more single batteries with low voltage, so the single batteries with voltage higher than the second threshold voltage VH need to be discharged and balanced for a longer time at the same current. If the average voltage is greater than or equal to the first threshold voltage VL1, it means that there are fewer single batteries with low voltage, so the single batteries with voltage higher than the second threshold voltage VH need to be discharged and balanced for a shorter time at the same current.
  • the comparison threshold can be adaptively increased, for example, the third threshold voltage VL2 is selected as 3.45V, the fourth threshold voltage VL3 is selected as 3.39V, and the lowest voltage in the single battery is obtained, wherein the lowest voltage refers to the lowest value of the voltage among all single batteries, and the lowest voltage is greater than or equal to the third threshold voltage VL2, and the battery with voltage higher than the second threshold voltage VH can be selected as the target battery.
  • the average voltage of the single battery is less than the first threshold voltage VL1 at this time, where the average voltage refers to the average value of the voltages of all single batteries, it means that there are more single batteries with low voltage, so the single battery with a voltage higher than the second threshold voltage VH is used as the target battery to perform the first discharge equalization. If the average voltage is greater than or equal to the first threshold voltage VL1, it means that there are fewer single batteries with low voltage, so it is necessary to perform the second discharge equalization of the target battery with a voltage higher than the second threshold voltage VH to ensure that it is not over-equalized, wherein the first charge is less than the second charge.
  • the fourth threshold voltage VL3 can be used to divide the discharge equalization charge accordingly to ensure the equalization performance. For example, if the lowest voltage is less than the third threshold voltage VL2, but not less than the fourth threshold voltage VL3, the battery with a voltage higher than the first threshold voltage VL1 is used as the target battery for discharge, and the third discharge equalization is performed. If the lowest voltage is less than the fourth threshold voltage VL3, the battery with a voltage higher than the first threshold voltage VL1 is used as the target battery for discharge, and the fourth discharge equalization is performed. The third electrical quantity is smaller than the fourth electrical quantity.
  • the target battery is subjected to corresponding balancing time, so that the battery can achieve battery charge balancing according to the battery working conditions.
  • the lowest voltage is greater than or equal to the third threshold voltage VL2. If the average voltage is less than the first threshold voltage VL1 at this time, it means that there are more single cells with low voltage, so it is necessary to select the first charge balancing for the single cells with voltage higher than the second threshold voltage VH, for example, 0.7% of the actual battery capacity for balancing.
  • the average voltage is greater than or equal to the first threshold voltage VL1, it means that there are fewer single cells with low voltage, so it is necessary to perform the second charge discharge balancing for the target battery with voltage higher than the second threshold voltage VH, for example, 0.5% of the actual battery capacity for balancing, to ensure that it is not over-balanced.
  • the battery with a voltage higher than the first threshold voltage VL1 is discharged and balanced for a third amount of time, for example, 1% of the actual battery capacity is balanced; if the lowest voltage is less than the fourth threshold voltage VL3, the battery with a voltage higher than the first threshold voltage VL1 is discharged and balanced for a fourth amount of time, for example, 2% of the actual battery capacity is balanced, so that appropriate amount of power balancing can be selected for batteries with different voltage balance degrees according to different working conditions.
  • the technical solution provided in the embodiment of the present application determines the current battery operating condition of the battery pack through the battery status of the single cell, and performs balancing judgment on the battery pack according to different battery operating conditions. If the balancing requirements are met, the target battery to be balanced in the battery pack is determined according to the battery status and the battery operating condition, thereby performing power balancing on the target battery. The target battery is judged and selected based on the battery operating condition, thereby avoiding the conditional restrictions brought about by the balancing judgment under a single operating condition, improving the flexibility of power balancing, improving the consistency of the battery pack, and improving the available capacity and available energy of the battery pack.
  • FIG2 is a schematic diagram of a flow chart of battery equalization judgment of a battery pack under a charging end condition provided by an embodiment of the present application.
  • the method steps include:
  • an equalization judgment is made according to the voltage of the single cell, and two threshold voltages are set, namely the first threshold voltage VL1 and the second threshold voltage VH.
  • the first threshold voltage VL1 is 3.5V
  • the second threshold voltage VH is 3.55V.
  • different first threshold voltages VL1 and second threshold voltages VH need to be selected.
  • the selection standard of the first threshold voltage VL1 is the voltage value corresponding to the single cell voltage reaching about 98.5% SOC at the end of charging
  • the selection standard of the second threshold voltage VH is the voltage value corresponding to the single cell voltage reaching about 99% SOC at the end of charging.
  • the size of SOC can be adjusted according to the voltage difference range required for battery balance. For example, if the SOC of the first threshold voltage VL1 and the SOC of the second threshold voltage VH differ greatly, the voltage interval composed of the first threshold voltage VL1 and the second threshold voltage VH becomes larger, that is, the range of battery balance becomes relatively smaller, which is equivalent to lowering the balance requirement. If the SOC of the first threshold voltage VL1 and the SOC of the second threshold voltage VH differ slightly, the voltage interval composed of the first threshold voltage VL1 and the second threshold voltage VH becomes smaller, that is, the range of battery balance becomes relatively larger, which is equivalent to increasing the balance requirement.
  • the voltages of all cells are less than the first threshold voltage VL1, it means that the voltages do not meet the requirements, and the cells do not need to be balanced.
  • all voltages are greater than the second threshold voltage VH, it means that the voltages and the SOC of the cells basically meet the charging requirements, and the cells do not need to be balanced.
  • some of the cells have voltages greater than the second threshold voltage VH and some are less than the first threshold voltage VL1, that is, the voltages between the cells are high and low, it means that there are consistency differences between the batteries, and it is determined that the battery pack needs to be balanced.
  • FIG3 is a schematic diagram of a process for determining a target battery to be balanced in a battery pack according to a battery state and a battery operating condition according to an embodiment of the present application.
  • the method steps include:
  • the third threshold voltage VL2 is less than the first threshold voltage VL1.
  • the third threshold voltage VL2 is 3.45V.
  • the selection standard of the third threshold voltage VL2 is the voltage value corresponding to the single cell voltage reaching about 97% SOC at the end of charging. Among them, the size of SOC can be adjusted according to the balanced voltage difference range required by the battery. The SOC corresponding to the third threshold voltage VL2 is set to be less than the SOC of the first threshold voltage VL1.
  • threshold voltages can be set for threshold division, thereby improving the battery's balanced judgment screening standard through threshold division, making the target battery screening better, and further improving the balanced effect.
  • the fourth threshold voltage VL3 is continued to be selected, and the fourth threshold voltage VL3 is less than the third threshold voltage VL2.
  • the fourth threshold voltage VL3 is 3.39V.
  • the selection standard of the fourth threshold voltage VL3 is the voltage value corresponding to the single cell voltage reaching about 96% SOC at the end of charging.
  • S320 determining a target battery according to the lowest voltage of the single battery, the first threshold voltage, the second threshold voltage and the third threshold voltage; wherein, if the lowest voltage of the single battery is greater than or equal to the third threshold voltage, the single battery with a marked voltage greater than the second threshold voltage is the target battery;
  • the single battery with a marking voltage greater than the first threshold voltage is the target battery.
  • the lowest voltage in the single cell is obtained, and the lowest voltage is greater than or equal to the third threshold voltage VL2.
  • the battery with a voltage higher than the second threshold voltage VH can be selected as the target battery for discharge balancing. If the average voltage of the single cell is less than the first threshold voltage VL1 at this time, it means that there are more single cells with low voltage. Therefore, the single cell with a voltage higher than the second threshold voltage VH is used as the target battery for discharge balancing at the same current for a longer time. If the average voltage is greater than or equal to the first threshold voltage VL1, it means that there are fewer single cells with low voltage.
  • the fourth threshold voltage VL3 can be used to divide the discharge balancing power accordingly to ensure the balancing performance. For example, if the lowest voltage is less than the third threshold voltage VL2 but not less than the fourth threshold voltage VL3, the battery with a voltage higher than the first threshold voltage VL1 is discharged as the target battery to perform the discharge balancing of the third power. If the lowest voltage is less than the fourth threshold voltage VL3, the battery with a voltage higher than the first threshold voltage VL1 is discharged as the target battery to perform the discharge balancing of the fourth power. The third power is less than the fourth power.
  • the first threshold voltage is the voltage value corresponding to the first preset charge state reached by the voltage of the single cell at the end of charging
  • the second threshold voltage is the voltage value corresponding to the second preset charge state reached by the voltage of the single cell at the end of charging
  • the third threshold voltage is the voltage value corresponding to the third preset charge state reached by the voltage of the single cell at the end of charging; wherein the second preset charge state is greater than the first preset charge state; and the first preset charge state is greater than the third preset charge state
  • first threshold voltages VL1, second threshold voltages VH and third threshold voltages VL2 need to be selected.
  • the fourth threshold voltage VL3 can be selected, and the corresponding voltage values under different charge states can be selected.
  • the equalization judgment screening standard of the battery is improved.
  • the first threshold voltage VL1 is 3.5V
  • the second threshold voltage VH is 3.55V
  • the third threshold voltage VL2 is 3.45V
  • the fourth threshold voltage VL3 is 3.39V.
  • the selection standard of the first threshold voltage VL1 is the voltage value corresponding to the single cell voltage reaching about 98.5% SOC at the end of charging
  • the selection standard of the second threshold voltage VH is the voltage value corresponding to the single cell voltage reaching about 99% SOC at the end of charging
  • the selection standard of the third threshold voltage VL2 is the voltage value corresponding to the single cell voltage reaching about 97% SOC at the end of charging
  • the selection standard of the fourth threshold voltage VL3 is the voltage value corresponding to the single cell voltage reaching about 96% SOC at the end of charging.
  • the size of SOC can be adjusted according to the voltage difference range required for battery balancing.
  • the voltage interval formed by the first threshold voltage VL1 and the second threshold voltage VH becomes larger, that is, the range of battery balancing becomes relatively smaller, which is equivalent to lowering the balancing requirement.
  • the voltage interval formed by the first threshold voltage VL1 and the second threshold voltage VH becomes smaller, that is, the range of battery balancing becomes relatively larger, which is equivalent to raising the balancing requirement.
  • the SOC corresponding to the third threshold voltage VL2 and the fourth threshold voltage VL3 is set to be smaller than the SOC of the first threshold voltage VL1, thereby improving the battery balancing judgment screening standard through threshold division, making the target battery screening better, and further improving the balancing effect.
  • FIG4 is a schematic diagram of a process for determining and selecting a target battery for battery balancing of a battery pack under a fully static working condition according to an embodiment of the present application.
  • the method steps include:
  • the voltage of the battery is the open circuit voltage (OCV), where the battery fully rests means that the BMS of the battery energy storage system does not power off, and the battery is considered to be fully rested when the current is less than the specified current and lasts for a preset time, for example, the current is less than 0.1C and lasts for 1 hour.
  • OCV open circuit voltage
  • the battery fully rests means that the BMS of the battery energy storage system does not power off
  • the battery is considered to be fully rested when the current is less than the specified current and lasts for a preset time, for example, the current is less than 0.1C and lasts for 1 hour.
  • the system time is read after it is powered on again. If the power-on time and the last power-off time exceed the preset time, the battery can also be considered to be fully rested.
  • the OCV-SOC relationship curve can determine the corresponding value of the open circuit voltage at different SOC values.
  • the OCV-SOC relationship curve includes a corresponding linear change interval. For example, taking the battery as an iron phosphate battery, the open circuit voltage range of the OCV-SOC linear interval is 2.5V-3.27V, and other voltages are considered to be in a nonlinear interval.
  • the reference capacity threshold is the threshold for judging whether a single cell needs to be balanced.
  • the OCV of the single cell is used to estimate the SOC value of the single cell, and the current battery capacity of each single cell is converted according to the SOC value.
  • the battery is balanced according to the difference in the capacity of each battery.
  • the average capacity of each battery is calculated, and the sum of the average capacity and the battery capacity multiplied by the weight (for example, a weight of 50%) is used as the reference capacity threshold.
  • the weight is the proportion of the average capacity to the battery capacity, and the proportion can be adjusted according to the actual situation, which has greater flexibility.
  • S430 Determine a target battery according to the battery capacity and a reference capacity threshold, wherein if the battery capacity is greater than the reference capacity threshold, mark the single cell as a target battery.
  • the battery whose capacity is higher than the reference capacity threshold is discharged and balanced.
  • the reference capacity threshold plus the capacity of the current actual capacity of the single cell can be used as a floating amount for judgment.
  • the battery whose capacity is higher than the reference capacity threshold + 1.5% * the current actual capacity is judged as the target battery.
  • the preset multiple can be adjusted according to the actual application. In the subsequent balancing, the battery needs to balance the discharge capacity of the current battery capacity of the single cell minus the reference capacity threshold.
  • FIG5 is a schematic diagram of a process for determining and selecting a target battery for battery balancing of a battery pack under a fully static working condition according to an embodiment of the present application.
  • the method steps include:
  • the voltage difference method is used to determine the battery that needs to be balanced and the balancing time, and the acquisition equipment is used to obtain the voltage of each single cell and the lowest voltage among the voltages, and the average voltage of the single cell is obtained based on the voltage of each single cell.
  • the first reference voltage is a threshold for judging whether or not the single cell needs to be balanced, and the average voltage and the lowest voltage are summed and averaged to obtain the first reference voltage.
  • S530 determining a target battery according to the voltage of the single battery and the first reference voltage, wherein if the difference between the voltage of the single battery and the first reference voltage is greater than a preset equalization value, marking the single battery as a target battery.
  • the single cell is judged to be a target cell that needs to be balanced.
  • the battery's balanced power or balanced time is set accordingly. Therefore, by dividing the cells according to the preset differences, the corresponding balanced time can be executed to improve the degree of balance. For example, if the voltage of a single cell minus the first reference voltage is ⁇ 30mv, it is judged that the battery needs to be balanced for 20 hours at the same current; if the voltage of a single cell minus the first reference voltage is ⁇ 15mv, it is judged that the battery needs to be balanced for 10 hours at the same current.
  • FIG6 is a schematic diagram of a flow chart of battery balancing judgment of a battery pack under charging conditions provided by an embodiment of the present application. Referring to FIG6 , the method steps include:
  • the maximum voltage Vr of a single cell during charging refers to the voltage corresponding to the moment when a significant inflection point appears in the voltage rise process of the single cell during charging. For example, taking a lithium iron phosphate battery as an example, the maximum voltage Vr is 3.4V.
  • a second reference voltage is obtained according to the average voltage of the single cell, the minimum voltage of the single cell and the preset voltage floating amount. When the voltage of the single cell is greater than the second reference voltage, it is determined that the single cell needs to be balanced.
  • the consistency of battery voltage can be gradually improved.
  • the equalization time is a fixed and conservative value, for some batteries, the equalization time may not be enough, so the consistency of battery voltage cannot be improved.
  • an equalization judgment method based on voltage difference is adopted.
  • the second reference voltage is the judgment threshold for screening the target battery. The average voltage and the minimum voltage are summed and then averaged and a certain voltage preset floating amount is added as the second reference voltage, where the voltage preset floating amount can be configured according to the battery performance.
  • the second reference voltage is (average voltage and minimum voltage)/2+20mV
  • the equalization time is set to 3 minutes. Because the voltage of the charging condition changes rapidly, the target battery is re-judged based on the voltage difference of the single cell after every 3 minutes.
  • the battery operating condition includes a charging end condition, a fully static condition, and a charging condition
  • the fully static condition includes a condition in which the open circuit voltage is within a linear change interval of the relationship between the open circuit voltage and the state of charge and a condition in which the open circuit voltage is within a nonlinear change interval of the relationship between the open circuit voltage and the state of charge;
  • the priority of performing battery balancing on the target battery is that the priority of the charging end condition is greater than the priority when the open circuit voltage is within the linear variation interval of the relationship between the open circuit voltage and the charge state;
  • the priority when the open circuit voltage is in the linear variation interval of the relationship between the open circuit voltage and the charge state is greater than the priority when the open circuit voltage is in the nonlinear variation interval of the relationship between the open circuit voltage and the charge state;
  • the priority when the open circuit voltage is within the nonlinear variation range of the relationship between the open circuit voltage and the state of charge is greater than the priority of the charging condition.
  • the battery pack has charging and static processes in the application, so the operating conditions of the battery pack include at least one of the charging end condition, the fully static condition and the charging condition. Therefore, by setting the balancing priority, when performing high-priority balancing under multiple conditions, the low-priority balancing process needs to wait until the high-priority balancing process is completed before it can be triggered, thereby improving the flexibility of battery balancing and improving the balancing effect.
  • the initial balancing mode is 0, the balancing mode 1 represents the balancing when the open circuit voltage is in the nonlinear change interval of the relationship between the open circuit voltage and the charge state, the balancing mode 2 represents the balancing when the open circuit voltage is in the nonlinear change interval of the relationship between the open circuit voltage and the charge state, and the balancing mode 3 represents the balancing of the charging end condition.
  • the balancing mode of the charging condition is stored in the storage, and the larger the value of the balancing mode, the higher the priority. Only when the waiting time for balancing of the high-priority balancing mode becomes 0, can the low-priority balancing mode be triggered.
  • the process of performing battery balancing on the target battery includes:
  • the balancing temperature of the single cell is obtained. If the balancing temperature is greater than the preset upper temperature limit, the balancing current is reduced; if the balancing temperature is less than the preset lower temperature limit, the balancing current is restored.
  • a preset upper temperature limit and a preset lower temperature limit are set, and the temperature of the single cell, i.e., the balancing temperature, is collected during the balancing process.
  • the balancing temperature is lowered by reducing the equivalent balancing current.
  • the balancing start instruction and the balancing stop instruction are executed alternately, so the balancing effective current is equivalent to being reduced to one-half, thereby reducing the balancing temperature.
  • the highest balancing temperature is less than the preset lower temperature limit, the balancing current is restored, the balancing start instruction is maintained, and the balancing process is continuously executed.
  • FIG. 7 is a schematic diagram of a battery balancing control system for a battery pack according to an embodiment of the present application, referring to FIG. 7 , including:
  • An acquisition module 110 is configured to acquire the battery status of a single battery in the battery pack
  • the operating condition determination module 120 is configured to determine the battery operating condition of the single battery according to the battery state
  • the judging module 130 is configured to judge whether the battery pack needs to be balanced according to the battery operating condition. If it is judged that the battery pack needs to be balanced, a target battery to be balanced in the battery pack is determined according to the battery state and the battery operating condition.
  • the balancing module 140 is configured to balance the power of the target battery.
  • the acquisition module 110 acquires the battery status of the single cells in the battery pack
  • the operating condition determination module 120 determines the current battery operating condition of the battery pack through the battery status of the single cells
  • the judgment module performs a balancing judgment on the battery pack for different battery operating conditions.
  • the target battery to be balanced in the battery pack is determined according to the battery status and the battery operating condition, and the balancing module 130 performs power balancing on the target battery, wherein the judgment module 140 makes a judgment and selects the target battery according to the battery operating condition, thereby avoiding the conditional restrictions brought about by the balancing judgment under a single operating condition, improving the flexibility of power balancing, improving the consistency of the battery pack, and improving the available capacity and available energy of the battery pack.
  • FIG8 is a schematic diagram of the structure of a battery management system provided by an embodiment of the present application.
  • the battery management system includes: a battery cluster 810 composed of single cells connected in series, a primary main control module (Management Battery Management Unit, MBMU), a secondary main control module (Second Battery Management Unit, SBMU), a voltage slave control module (Battery Management Unit, VCMU), a temperature acquisition slave board (Battery Temperature Unit, TCMU), a high-voltage acquisition board (High-Voltage Management Unit, HMU) and a display control (Human interface, HMI).
  • a battery cluster 810 composed of single cells connected in series
  • a primary main control module Management Battery Management Unit, MBMU
  • SBMU Secondary main control module
  • VCMU voltage slave control module
  • VCMU temperature acquisition slave board
  • TCMU Battery Temperature Unit
  • HMU High-Voltage Management Unit
  • HMI High-Voltage Management Unit
  • the battery management system includes SBMU and VCMU with integrated balancing module in the balancing control. Among them, the corresponding functions of the working condition determination module and the judgment module are integrated in the SBMU.
  • the balancing strategy is mainly determined by the SBMU to judge the balancing, start and stop the balancing operation.
  • the SBMU sends the corresponding start or stop balancing command to the VCMU.
  • the VCMU controls the opening and closing of the balancing hardware according to the control command of the SBMU and executes the balancing process of the single cell.
  • the balancing command is implemented through CAN communication, and the sending is sent in a periodic manner.
  • the SBMU periodically sends the balancing command to the VCMU.
  • the VCMU After receiving the balancing command, the VCMU starts or shuts down the balancing hardware and sends the balancing execution status through the CAN bus.
  • the VCMU and TCMU collect the voltage, temperature, current and other parameters of the single cell. Among them, the implementation of the functions such as the acquisition module and the balancing module can be integrated in the VCMU.
  • the battery management system has a wealth of external interfaces that can meet the application requirements of various occasions. These interfaces include: voltage acquisition input interface, temperature acquisition input interface, fan control output interface, fan signal feedback input interface, heating control output interface, CAN2.0 interface, Ethernet interface, RS485 interface, dry contact output interface, switch input/output interface, current high-speed acquisition input interface, and high-voltage signal acquisition input interface.
  • FIG9 is a flowchart of another balancing control method provided by an embodiment of the present application.
  • the control entry is called every preset time, illustratively, once every 200ms, and execution begins;
  • S720 relevant fault information of balancing control is obtained, such as single cell voltage detection fault, temperature detection fault, current detection fault, V-CAN communication fault, storage fault and other information.
  • S730 determine whether the fully static working condition is met, if so, S740, mark the balancing according to the fully static working condition of the battery. If not, skip S740.
  • S750 determine whether the working condition after charging is satisfied, if satisfied, S760, mark the balance judgment according to the working condition after charging is satisfied. If not satisfied, skip S760.
  • S770 determine whether the charging end condition is met, if so, S780, mark the balance according to the charging end condition. If not, skip S780.
  • the battery management system has no faults related to prohibiting balancing, such as single cell voltage detection fault, temperature detection fault, current detection fault, V-CAN communication fault, EE fault, etc., battery temperature ⁇ 45°C, and balancing temperature ⁇ 100°C.
  • the difference between the accumulated total voltage of each single cell received by the SBMU and the total voltage detected is less than 10V.
  • the lowest single cell voltage is greater than the lower limit of the voltage threshold for fully static judgment balancing (such as 3.1V). There is no high priority balancing mode.
  • the SBMU determines that the above conditions are met, it triggers a fully static judgment balancing, that is, S800 calls the judgment function to select the target battery, and S810, the balancing is executed.
  • the SBMU determines the battery that needs to be balanced and the corresponding balancing time based on the battery single cell voltage, minimum voltage, average voltage, OCV-SOC table, etc., and the balancing time is saved in the storage for calling.
  • the working condition judgment and balancing conditions are as follows: the battery management system has no faults related to prohibiting balancing, such as single cell voltage detection fault, temperature detection fault, current detection fault, V-CAN communication fault, storage fault, etc., the battery temperature is ⁇ 45°C, and the balancing temperature is ⁇ 100°C.
  • the lowest single cell voltage is greater than the threshold value (such as 3.1V) for judging the balancing voltage.
  • the current is less than 0.35C, and the maximum voltage of the single cell remains greater than Vr (such as 3.4V) for more than 1 minute. Every 3 minutes, it is judged whether the above conditions are met. If they are met, it triggers the working condition judgment and balancing after charging is completed.
  • S800 calls the judgment function to select the target battery, and judges that the battery with a single cell voltage higher than (average voltage + minimum voltage)/2+preset floating amount (configurable, such as 20mV) needs to be balanced, and S810, balancing is executed.
  • the balancing time is fixed at 3 minutes, and this time is not saved to the storage.
  • the conditions for judging the equalization of the charging end condition are: the battery management system has no faults related to prohibiting equalization, such as single cell voltage detection fault, temperature detection fault, current detection fault, V-CAN communication fault, communication fault, etc., the battery temperature is ⁇ 45°C, and the equalization temperature is ⁇ 100°C. The lowest voltage of the single cell is greater than the threshold value allowed for judging the equalization voltage (such as 3.1V).
  • the SBMU determines whether the above conditions are met. If they are met, it triggers a charge end condition judgment equalization, that is, S800 calls the judgment function to select the target battery.
  • the SBMU judges the battery that needs to be balanced based on the battery's highest voltage, lowest voltage, average voltage, VH, VL1, VL2, VL3, etc. S810, balance execution, and balance is performed according to the corresponding balance time.
  • the balance time is saved in the storage, and the balance mode is set to 3.
  • S820 determines whether the conditions for starting balancing are met, such as single cell voltage detection failure, temperature detection failure, current detection failure, V-CAN communication failure, storage failure, battery temperature ⁇ 45°C and balancing temperature ⁇ 100°C, etc., and the lowest single cell voltage is greater than the threshold value allowed to start balancing voltage (such as 3.1V), then it means that the start conditions are met, and S830 calls the start function to start the operation.
  • the conditions for starting balancing such as single cell voltage detection failure, temperature detection failure, current detection failure, V-CAN communication failure, storage failure, battery temperature ⁇ 45°C and balancing temperature ⁇ 100°C, etc.
  • the threshold value allowed to start balancing voltage such as 3.1V
  • S840 determines whether the condition for stopping balancing is met, where the condition for stopping balancing includes the battery management system having a fault related to prohibiting balancing, such as a single cell voltage detection fault, a temperature detection fault, a current detection fault, a V-CAN communication fault, and a storage fault, as well as a battery temperature ⁇ 45°C, a balancing temperature ⁇ 100°C, etc.
  • the lowest voltage is less than or equal to the stop balancing voltage threshold (such as 3.08V).
  • the SBMU will stop balancing all batteries.
  • SBMU starts balancing, it needs to count the balancing time.
  • the balancing flag of the cell needs to be cleared.
  • the balancing time of all cells is completed, the balancing stops.
  • S850 calls the stop balancing function.
  • S850 will mark the need to clear balancing when it determines that the time interval between the last power-off time and the current power-on time of the BMS exceeds 240 hours, and the battery management system has no faults related to prohibiting balancing.
  • the SBMU receives the voltage of each battery cell, the accumulated total voltage and the detected total voltage difference are less than 10V.
  • S870 will call the clear balancing function to clear the stored balancing time.
  • FIG10 is a schematic diagram of a flow chart of equalization judgment provided by an embodiment of the present application.
  • the judgment flow chart includes a charging end condition, a battery fully static condition, and a condition after charging is completed.
  • the method steps include:
  • S900 determine the entry of the balancing function, S901, stop balancing, S910, determine whether it is the charging end condition, if it is the charging end condition, S920, clear the balancing mark, balancing mode and balancing time, S930, determine whether the maximum voltage of the single cell is less than the first threshold voltage VL1, such as 3.5V, if the maximum voltage is less than the first threshold voltage VL1, it means that the voltage of all single cells is less than the first threshold voltage VL1, which means that the voltage does not meet the requirement, and at this time, the single cells do not need to be balanced.
  • the first threshold voltage VL1 such as 3.5V
  • the balancing time is set to the balancing time corresponding to 0.7% of the actual capacity of the battery.
  • the balancing time is set to the balancing time corresponding to 0.5% of the actual battery capacity.
  • S990 updates the balancing mark and balancing time of each battery, and sets the balancing mode to balancing mode 3.
  • S1001 saves the balancing time and balancing mode.
  • the minimum voltage is less than the third threshold voltage VL2, then S1002, determine whether the minimum voltage of the single battery is less than the fourth threshold voltage VL3, such as 3.39V; if the minimum voltage is greater than the third threshold voltage VL2, S1003, set the balancing time for the battery whose voltage is higher than the first threshold voltage VL1 to 1% of the balancing time corresponding to the actual capacity of the battery; if the minimum voltage is less than the third threshold voltage VL2, S1004, set the balancing time for the battery whose voltage is higher than the first threshold voltage VL1 to 2% of the balancing time corresponding to the actual capacity of the battery.
  • the fourth threshold voltage VL3 such as 3.39V
  • S1005 determine whether the battery is in a fully static condition, and whether the current balancing mode priority is less than balancing mode 3. If the battery is in a fully static condition, S1006, clear the balancing mark, S1007, calculate the reference capacity threshold and the first reference voltage, S1008, determine whether the open circuit voltage is in a linear interval, if it is in the linear interval, then S1009, calculate the difference between the battery capacity of each single cell and the reference capacity threshold, and discharge and balance the battery whose battery capacity is higher than the reference capacity threshold.
  • the reference capacity threshold plus the capacity of the current actual capacity of the single cell preset multiple can be used as a floating amount for judgment, for example, the battery capacity higher than the reference capacity threshold + 1.5% * the current actual capacity is judged as the target battery.
  • the preset multiple can be selected and adjusted according to the actual application.
  • the battery needs to balance the discharge capacity of the current battery capacity of the single cell minus the reference capacity threshold.
  • S1010 update the balancing mark and balancing time of each single cell, and set the balancing mode to balancing mode 2.
  • S1011 save the balancing time and balancing mode.
  • S1012 determines whether the current balancing mode priority is lower than balancing mode 2, if so, then S1013, the difference between the voltage of each single cell and the first reference voltage exceeds the configuration value, and the voltage of the single cell - the first reference voltage ⁇ 30mv, then the battery cell is balanced for 20 hours; if the voltage of the single cell - the first reference voltage ⁇ 15mv, then the battery cell is balanced for 10 hours.
  • S1014 update the balancing mark and balancing time of each single cell, and set the balancing mode to balancing mode 1, S1011, save the balancing time and balancing mode.
  • S1015 determines whether it is in a state after charging is completed. If so, S1016 clears the equalization mark, S1017 calculates the second reference voltage, S1018 marks the cells whose voltages of the individual cells and the second reference voltage differ by more than the configured value as cells that need to be equalized. S1019 sets the equalization time to 3 minutes.
  • FIG11 is a flowchart of a processing equalization judgment provided by an embodiment of the present application.
  • S1100 process the equalization entry, S1101, determine whether the equalization is in the on state, if it is in the on state, S1102, whether the time of equalization according to the pressure difference in the working condition after the charging is completed is greater than zero, if it is S1103, the time of equalization according to the pressure difference in the working condition after the charging is completed is reduced by 200ms, S1104, whether the time of equalization according to the pressure difference in the working condition after the charging is completed is zero, if not, return to S1102. If it is S1105, clear the equalization flag of each battery and stop the pressure difference equalization.
  • S1106 determine whether to update the equalization flag to enable or update the equalization time, if it is S1107, update the equalization flag according to the equalization time, S1108, determine whether the remaining equalization time is not zero, if it is S1109, start the equalization, S1110 determine whether the highest equalization temperature of the battery is greater than or equal to 80°C, if it is greater than or equal to 80°C, S1111, reduce the equivalent equalization current. If it is less than 80°C, then S1112, determine whether the highest equalization temperature of the battery is less than 70°C. If it is less than 70°C, then S1113, the equivalent equalization current returns to normal. S1114, determine whether the current equalization state is closed or reaches the 30S equalization time of closing. If so, then S1115, turn off the equalization instruction of all batteries. If not, S1116 sends a start or turn off battery equalization instruction according to the equalization flag.
  • FIG12 is a schematic diagram of the circuit structure of a balancing module provided in an embodiment of the present application
  • FIG13 is a schematic diagram of the structure of a balancing branch provided in an embodiment of the present application.
  • the balancing branch includes: a control unit 220 and a plurality of balancing branches 210 , each balancing branch 210 being connected to a single cell.
  • control unit can include an ADBMS6815 battery management chip, and resistors R1, R2, R4, and R5 are voltage-dividing resistors for NTC temperature measurement.
  • the resistance value under the current temperature conditions is calculated by collecting the voltage-dividing size on resistor R1. By looking up the R-T table of the NTC sensor used in the project, the temperature value corresponding to the resistance value can be found.
  • the power selection reserve is sufficient to meet the design requirements.
  • the start and stop of the balancing circuit is controlled by closing and opening the electronic switch Q1.
  • the electronic switch Q1 can be an NMOS switch.
  • the control unit outputs a control signal to the control terminal 1 of the electronic switch Q1, and the first terminal 2 and the second terminal 3 of the electronic switch Q1 are turned on.
  • the voltage of the positive battery BAT01_01 of the single cell passes through the resistor R2, the resistor R3, the resistor R4, and the electronic switch Q1 to the negative battery, realizing the balanced discharge process.
  • the control unit outputs a control signal to turn off the electronic switch Q1.

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Abstract

本申请公开了一种电池组的电量均衡方法及系统、电池管理系统，方法包括：获取电池组中的单体电池的电池状态；根据电池状态确定单体电池的电池工况；根据电池工况对电池组是否需要均衡进行判断，若判断电池组需要均衡处理，则根据电池状态和电池工况确定电池组中需均衡的目标电池；对目标电池进行电量均衡。

Description

电池组的电量均衡方法及系统、电池管理系统
本申请要求在2022年10月26日提交中国专利局、申请号为202211320222.2的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及动力电池技术领域，例如涉及电池组的电量均衡方法及系统、电池管理系统。
 背景技术
目前，电动汽车的电池组大多由单体电池串联而成，由于单体电池在制造过程中以及在电池组的循环充放电过程中会产生差异，导致各个单体电池在额定容量、电压、内阻等方面不完全一致。电池组的不一致性是导致整组电池性能下降的重要因素，不均衡的电池组会降低电池组容量和能量的利用率，降低电池组输入输出功率水平，缩短了电池组的使用寿命。为了提高电池包使用过程中的一致性，需要根据电芯间的不均衡度对电池包进行均衡。
相关技术中通常在组装成电池包前对电池进行筛选，在电池组的使用初期，单体电池的一致性较好，但随着电池组使用时间的不断增加，仍会存在不一致性。在电池组应用过程中通常采用均衡调节，但相关技术在均衡过程中通常采用固定的运行工况下进行均衡，均衡控制还存在不足，从而影响电池组一致性，影响均衡效果。
 技术问题
本申请提供一种电池组的电量均衡方法及系统、电池管理系统，增加了均衡灵活性，提升了电池组一致性，提升电池组的可用容量和可用能量。
 技术解决方案
第一方面，本申请实施例提供一种电池组的电量均衡方法，包括：
获取电池组中的单体电池的电池状态；
根据所述电池状态确定所述单体电池的电池工况；
根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
对所述目标电池进行电量均衡。
第二方面，本申请实施例还提供一种电池组的电池均衡控制系统，包括：
获取模块，设置于获取电池组中的单体电池的电池状态；
工况确定模块，设置于根据所述电池状态确定所述单体电池的电池工况；
判断模块，设置于根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
均衡模块，设置于对所述目标电池进行电量均衡。
第三方面，本申请实施例还提供一种电池管理系统，包括电池组的电池均衡控制系统，所述电池组的电池均衡控制系统包括：
获取模块，设置于获取电池组中的单体电池的电池状态；
工况确定模块，设置于根据所述电池状态确定所述单体电池的电池工况；
判断模块，设置于根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
均衡模块，设置于对所述目标电池进行电量均衡；
所述电池管理系统包括：二级主控模块、电压从控模块和温度采集从板；
其中，所述工况确定模块和所述判断模块集成于所述二级主控模块中，所述获取模块集成于所述电压从控模块和所述温度采集从板中，所述均衡模块集成于所述电压从控模块中。
 有益效果
本申请实施例提供的技术方案，通过单体电池的电池状态确定电池组的当前电池工况，针对不同的电池工况条件，对电池组进行均衡判断，若符合均衡要求，根据电池状态和电池工况确定电池组中需均衡的目标电池，从而对目标电池进行电量均衡，其中，依据电池工况，进行判断并选择目标电池，避免了单一的运行工况下进行均衡判断带来的条件限制，提高了电量均衡的灵活性，提升了电池组一致性，提升了电池组的可用容量和可用能量。
 附图说明
图1为本申请实施例提供的一种电池组的电量均衡方法的流程示意图；
图2为本申请实施例提供一种充电结束工况下电池组的电池均衡判断的流程示意图；
图3为本申请实施例提供一种根据电池状态和电池工况确定电池组中需均衡的目标电池的流程示意图；
图4为本申请实施例提供一种充分静置工况下电池组的电池均衡判断选取目标电池的流程示意图；
图5为本申请实施例提供又一种充分静置工况下电池组的电池均衡判断选取目标电池的流程示意图；
图6为本申请实施例提供一种充电工况下电池组的电池均衡判断的流程示意图；
图7为本申请实施例提供一种电池组的电池均衡控制系统的结构示意图；
图8为本申请实施例提供一种电池管理系统的结构示意图；
图9为本申请实施例提供一种均衡控制方法的流程示意图；
图10为本申请实施例提供一种均衡判断的流程示意图；
图11为本申请实施例提供一种处理均衡判断的流程示意图；
图12为本申请实施例提供一种均衡模块的电路结构示意图；
图13为本申请实施例提供一种均衡支路结构示意图。
 本发明的实施方式
图1为本申请实施例提供的一种电池组的电量均衡方法的流程示意图，本实施例可适用于电池均衡情况，该方法可以由电池均衡控制系统来执行，该装置可采用硬件和/或软件的方式来实现。该方法包括如下步骤：
S110、获取电池组中的单体电池的电池状态；
其中，电池状态指单体电池的运行状态，运行状态通过单体电池的电流、电压和温度等参数进行表征。单体电池的运行状态的获取可以通过相应的传感器和传感芯片等采集设备进行采集。
S120、根据电池状态确定单体电池的电池工况；
示例性的，电池组在应用中存在充电以及静置过程，因此电池组的运行工况至少包括充电结束工况、充分静置工况和充电工况至少一种。示例性的，充电结束工况指的是充电降流结束，电池充满时刻的状态。充分静置工况指电池的电流在小于预设电流下持续预设时间，可以认为电池充分静置，或者电池管理系统低压下电到再次上电后读取系统时间，如果上电时间和上次下电时间超过预设时间，也认为电池充分静置。
充电工况包括充电中工况和充电结束后工况，充电中工况是指单体电池在一定时间能持续存在预设电流以上的充电电流，例如，单体电池持续5秒超过2A以上的充电电流。充电结束后工况指的是从充电工况或充电结束工况时存在预设区间内的电流持续超过预设时间，即跳转到充电结束后工况，例如，若有-2A到10A以内的电流持续超过1分钟，即跳转到充电结束后工况。若有超过10A的放电电流，则跳转为非充电状态。其中，预设时间和相应的电压设置可以根据电池类型进行选择设置。
S130、根据电池工况对电池组进行均衡判断，若判断电池组是否需要均衡处理，则根据电池状态和电池工况确定电池组中需均衡的目标电池；
示例性的，根据确定的电池工况，进行判断相应工况下的电池组的不均衡程度，若需要执行均衡，则依据当前对应的工况，根据电池的电流、电压等参数确定需要进行均衡的电池并进行标记，即得到目标电池。示例性的，以充电结束工况为例判断均衡，根据电池性能确定第一阈值电压和第二阈值电压，示例性的，以电池为磷酸铁理电池为例，选取第一阈值电压VL1为3.5V，第二阈值电压VH为3.55V，若所有单体电池的电压都小于第一阈值电压VL1，则说明所有单体电池的电压都低，此时电池均不需要均衡。若所有单体电池电压都大于第二阈值电压VH，则说明所有单体电池的电压都达到电压目标，此时电池均不需要均衡。若部分单体电池的电压大于第二阈值电压VH且部分单体电池的电压小于第一阈值电压VL1，也就是说，电池的电压存在高低不均的情况，则电池存在不均衡，则说明单体电池需要进行均衡调整。
在充电结束工况下，单体电池的平均电压小于第一阈值电压VL1，则说明电压低的单体电池较多，因此需要对电压高于第二阈值电压VH的单体电池进行同电流下较长时间的放电均衡，如果平均电压大于等于第一阈值电压VL1，说明电压低的单体电池较少，因此需要对电压高于第二阈值电压 VH的单体电池进行同电流下较短时间的放电均衡。为了提高均衡程度的判断，可以适应性的增加比较阈值，例如，增加选取第三阈值电压VL2为3.45V，第四阈值电压VL3为3.39V，获取单体电池中的最低电压，其中，最低电压是指所有单体电池中电压的最低值，最低电压大于或等于第三阈值电压VL2，可以选择电压高于第二阈值电压VH的电池作为目标电池。如果此时单体电池的平均电压小于第一阈值电压VL1，其中，平均电压是指所有单体电池的电压的平均值，则说明电压低的单体电池较多，因此将电压高于第二阈值电压 VH的单体电池作为目标电池，进行第一电量的放电均衡，如果平均电压大于等于第一阈值电压VL1，说明电压低的单体电池较少，因此需要对电压高于第二阈值电压 VH的目标电池进行第二电量的放电均衡，保证不过度均衡，其中第一电量小于第二电量。如果最低电压小于第三阈值电压VL2，则将电压高于第一阈值电压VL1的电池作为目标电池进行放电，为了进一步，细分放电均衡电量，可以了利用第四阈值电压VL3，相应的划分放电均衡的电量，保证均衡性能，例如如果最低电压小于第三阈值电压VL2，但不小于第四阈值电压 VL3，则将电压高于第一阈值电压VL1的电池作为目标电池进行放电，进行第三电量的放电均衡，如果最低电压小于第四阈值电压 VL3，则将对电压高于第一阈值电压VL1的电池作为目标电池进行放电，进行第四电量的放电均衡。其中，第三电量小于第四电量。
S140、对目标电池进行电量均衡。
示例性的，在相应的工况下，对目标电池执行相应的均衡时间，从而使电池依据电池工况，实现电池的电量均衡。示例性的，在充电结束工况下，最低电压大于或等于第三阈值电压VL2，若此时平均电压小于第一阈值电压VL1，则说明电压低的单体电池较多，因此需要对电压高于第二阈值电压 VH的单体电池选取第一电量的均衡，例如，0.7%电池实际容量进行均衡。如果平均电压大于或等于第一阈值电压VL1，说明电压低的单体电池较少，因此需要对电压高于第二阈值电压VH的目标电池进行第二电量的放电均衡，例如为0.5%电池实际容量的均衡，保证不过度均衡。如果最低电压小于第三阈值电压VL2，但不小于第四阈值电压VL3，对电压高于第一阈值电压VL1的电池进行第三电量的放电均衡，例如，1%电池实际容量进行均衡，如果最低电压小于第四阈值电压VL3，对电压高于第一阈值电压VL1的电池进行第第四时间的放电均衡，例如，为2%电池实际容量的进行均衡，从而可以依据不同的工况，不同电压均衡度的电池选取适当的电量均衡。
本申请实施例提供的技术方案，通过单体电池的电池状态确定电池组的当前电池工况，针对不同的电池工况条件，对电池组进行均衡判断，若符合均衡要求，根据电池状态和电池工况确定电池组中需均衡的目标电池，从而对目标电池进行电量均衡，其中，依据电池工况，进行判断并选择目标电池，避免了单一的运行工况下进行均衡判断带来的条件限制，提高了电量均衡的灵活性，提升了电池组一致性，提升了电池组的可用容量和可用能量。
图2为本申请实施例提供一种充电结束工况下电池组的电池均衡判断的流程示意图，参见图2，方法步骤包括：
S210、根据单体电池确定第一阈值电压和第二阈值电压；其中，第一阈值电压小于第二阈值电压；
示例性的，在充电结束时按照单体电池的电压情况进行均衡判断，设置两个阀值电压，即第一阈值电压VL1和第二阈值电压VH。示例性的，电池为磷酸铁理电池，则第一阈值电压VL1为3.5V，第二阈值电压VH为3.55V。针对不同类型的电池，需选取不同的第一阈值电压VL1和第二阈值电压VH。示例性的，第一阈值电压VL1选取标准为充电结束时刻单体电压达到约98.5%SOC对应的电压值，第二阈值电压VH的选取标准为充电结束时刻单体电压达到约99%SOC对应的电压值。其中，SOC的大小可以根据电池需要均衡压差范围进行调节，例如，第一阈值电压VL1的SOC和第二阈值电压VH的SOC相差较大，则第一阈值电压VL1和第二阈值电压VH组成的电压区间变大，即电池需要均衡的范围相对变小，相当于降低了均衡要求，第一阈值电压VL1的SOC和第二阈值电压VH的SOC相差较小，则第一阈值电压VL1和第二阈值电压VH组成的电压区间变小，即电池需要均衡的范围相对变大，相当于提高了均衡要求。
S220、获取电池组中每一单体电池的电压；
S230、根据单体电池的电压、第一阈值电压和第二阈值电压之间的关系对所述电池组进行均衡判断；其中，若至少部分单体电池的电压小于第一阈值电压，且至少部分单体电池的电压大于第二阈值电压，则判断电池组需要均衡处理。
示例性的，若所有单体电池的电压都小于第一阈值电压VL1，则说明电压均达不到要求，此时单体电池均不需要进行均衡。若所有电压都大于第二阈值电压VH，则说明电压和单体电池的SOC基本达到充电要求，此时单体电池也不需要均衡。若单体电池中存在部分电压大于第二阈值电压VH且部分电池小于第一阈值电压VL1，也就是说，单体电池之间的电压存在有高有低的情况，则说明电池之间存在一致性差异，则判断此时的电池组需要进行均衡处理。
基于上述实施例，图3为本申请实施例提供一种根据电池状态和电池工况确定电池组中需均衡的目标电池的流程示意图，参见图3，方法步骤包括：
S310、根据单体电池确定第三阈值电压，其中，第三阈值电压小于第一阈值电压；
示例性的，针对不同类型的电池，继续需选取不同的第三阈值电压VL2，第三阈值电压VL2小于第一阈值电压VL1，示例性的，以电池为磷酸铁理电池为例，第三阈值电压VL2为3.45V，示例性的，第三阈值电压VL2选取标准为充电结束时刻单体电压达到约97%SOC对应的电压值。其中，SOC的大小可以根据电池需要均衡压差范围进行调节，第三阈值电压VL2对应的SOC设置小于第一阈值电压VL1的SOC，可以设置多组阈值电压进行阈值划分，从而通过阈值划分提高电池的均衡判断筛选标准，使目标电池筛选更优，进一步提升均衡效果。例如，针对不同类型的电池，继续选取第四阈值电压VL3，第四阈值电压VL3小于第三阈值电压VL2，示例性的，以电池为磷酸铁理电池为例，第四阈值电压VL3为3.39V。示例性的，第四阈值电压VL3的选取标准为充电结束时刻单体电压达到约96%SOC对应的电压值。
S320、根据单体电池的最低电压、第一阈值电压、第二阈值电压和第三阈值电压确定目标电池；其中，若单体电池的最低电压大于或等于第三阈值电压，则标记电压大于第二阈值电压的单体电池为目标电池；
若单体电池的最低电压小于第三阈值电压，则标记电压大于第一阈值电压的单体电池为目标电池。
示例性的，获取单体电池中的最低电压，最低电压大于或等于第三阈值电压VL2，可以选择电压高于第二阈值电压VH的电池作为目标电池，进行放电均衡。如果此时单体电池的平均电压小于第一阈值电压VL1，则说明电压低的单体电池较多，因此电压高于第二阈值电压VH的单体电池作为目标电池，进行同电流下较长时间的放电均衡，如果平均电压大于等于第一阈值电压VL1，说明电压低的单体电池较少，因此需要对电压高于第二阈值电压VH的目标电池进行同电流下较短时间的放电均衡。如果最低电压小于第三阈值电压VL2，则将电压高于第一阈值电压VL1的电池作为目标电池进行放电。为了细分放电均衡电量，可以利用第四阈值电压VL3，相应的划分放电均衡的电量，保证均衡性能，例如，如果最低电压小于第三阈值电压VL2，但不小于第四阈值电压 VL3，则将电压高于第一阈值电压VL1的电池作为目标电池进行放电，进行第三电量的放电均衡，如果最低电压小于第四阈值电压 VL3，则将对电压高于第一阈值电压VL1的电池作为目标电池进行放电，进行第四电量的放电均衡。其中，第三电量小于第四电量。
示例性的，第一阈值电压为充电结束时刻单体电池的电压达到第一预设电荷状态对应的电压值；第二阈值电压为充电结束时刻单体电池的电压达到第二预设电荷状态对应的电压值；第三阈值电压为充电结束时刻单体电池的电压达到第三预设电荷状态对应的电压值；其中，第二预设电荷状态大于第一预设电荷状态；第一预设电荷状态大于第三预设电荷状态；
示例性的，针对不同类型的电池，需选取不同的第一阈值电压VL1、第二阈值电压VH和第三阈值电压VL2，为了增加均衡判断精度，示例性的，可以继续选取第四阈值电压VL3，选取不同电荷状态下对应的电压值，通过设置多组阈值电压，提高电池的均衡判断筛选标准。示例性的，以电池为磷酸铁理电池为例，第一阈值电压VL1为3.5V，第二阈值电压VH为3.55V，第三阈值电压VL2为3.45V，第四阈值电压VL3为3.39V。其中，第一阈值电压VL1选取标准为充电结束时刻单体电压达到约98.5%SOC对应的电压值，第二阈值电压VH的选取标准为充电结束时刻单体电压达到约99%SOC对应的电压值，第三阈值电压VL2选取标准为充电结束时刻单体电压达到约97%SOC对应的电压值，第四阈值电压VL3的选取标准为充电结束时刻单体电压达到约96%SOC对应的电压值。其中，SOC的大小可以根据电池需要均衡压差范围进行调节，例如，第一阈值电压VL1的SOC和第二阈值电压VH的SOC相差较大，则第一阈值电压VL1和第二阈值电压VH组成的电压区间变大，即电池需要均衡的范围相对变小，相当于降低了均衡要求，第一阈值电压VL1的SOC和第二阈值电压VH的SOC相差较小，则第一阈值电压VL1和第二阈值电压VH组成的电压区间变小，即电池需要均衡的范围相对变大，相当于提高了均衡要求。第三阈值电压VL2和第四阈值电压VL3对应的SOC设置小于第一阈值电压VL1的SOC，从而通过阈值划分提高电池的均衡判断筛选标准，使目标电池筛选更优，进一步提升均衡效果。
图4为本申请实施例提供一种充分静置工况下电池组的电池均衡判断选取目标电池的流程示意图，参见图4，方法步骤包括：
S410、当单体电池充分静置后的开路电压处于开路电压与电荷状态关系的线性变化区间内时，获取单体电池的电池容量和单体电池的平均容量；
示例性的，电池充分静置后，电池的电压为开路电压（Open circuit voltage，OCV），其中，电池充分静置指电池储能系统的BMS不下电，在电流小于规定的电流并且持续预设时间，例如电流小于0.1C并且持续1小时，则可认为电池充分静置。或者BMS低压下电的情况，待再次上电后读取系统时间，如果上电时间和上次下电时间超过预设时间，也可以认为电池充分静置。
OCV-SOC关系曲线可以确定在不同的SOC值下开路电压的对应值。其中，根据电池的类型，OCV-SOC关系曲线包括相应的线性变化区间，示例性的，以电池为磷酸铁理电池为例，OCV-SOC线性区间的开路电压范围为2.5V-3.27V，而认为其他电压处于非线性区间。
S420、根据电池容量和平均容量确定基准容量阈值；
示例性的，基准容量阈值是单体电池需要均衡的判断阈值，在OCV-SOC线性变化的区间内，利用单体电池的OCV去估算出单体电池的SOC值，并根据SOC值换算出各单体电池当前的电池容量，依据各电池容量的差异来对电池实施均衡控制。计算各电池的平均容量，将平均容量与电池容量乘以权重（例如取50%的权重）的相加值作为基准容量阈值。考虑平均容量与电池容量，避免选取参数单一，提高数据精确性。其中，权重是平均容量与电池容量所占的比重，该比重依实际情况可调，具有更大的灵活性。
S430、根据电池容量和基准容量阈值确定目标电池，其中，若电池容量大于基准容量阈值，则标记单体电池为目标电池。
示例性的，将电池容量高于基准容量阈值的电池进行放电均衡，示例性的，为了保证不被过度均衡，可以将基准容量阈值加上单体电池当前的实际容量预设倍数的容量，作为浮动量进行判断，例如，将电池容量高于基准容量阈值+1.5%*当前的实际容量判断为目标电池。其中，预设倍数可以根据实际应用选择调整。后续均衡中，电池需要均衡放电容量为该单体电池当前的电池容量-基准容量阈值。
图5为本申请实施例提供又一种充分静置工况下电池组的电池均衡判断选取目标电池的流程示意图，参见图5，方法步骤包括：
S510、当开路电压处于开路电压与电荷状态关系的非线性变化区间内时，获取单体电池的电压、单体电池的平均电压和单体电池的最低电压；
示例性的，开路电压在OCV-SOC非线性变化的区间内时，不能根据OCV得出各单体电池的SOC值，因此采用压差法判断需要均衡的电池和均衡时间，利用采集设备获取个单体电池的电压以及电压中的最低电压，并根据每个单体电池的电压获得单体电池的平均电压。
S520、根据单体电池的平均电压和单体电池的最低电压确定第一基准电压；
示例性的，第一基准电压是单体电池需要均衡的判断阈值，将平均电压和最低电压求和后做平均作为第一基准电压。
S530、根据单体电池的电压和第一基准电压确定目标电池，其中，若单体电池的电压和第一基准电压的差值大于均衡预设值，则标记单体电池为目标电池。
示例性的，若单体电池的电压与第一基准电压的差值大于或等于预设差值，则判断该单体电池为需要均衡的目标电池。通过设置不同的预设差值，对应设置电池的均衡电量或均衡时间，因此通过根据预设差值进行分档，可以执行相应的均衡时间，提高均衡度。例如，单体电池的电压-第一基准电压≥30mv，则判断该电芯在同电流下需要均衡20小时；如果单体电池的电压-第一基准电压≥15mv，则判断该电芯在同电流下需要均衡10小时。
图6为本申请实施例提供一种充电工况下电池组的电池均衡判断的流程示意图，参见图6，方法步骤包括：
S610、获取单体电池的电压、单体电池的平均电压、单体电池的最低电压和单体电池充电过程的最大电压；
其中，单体电池充电过程的最大电压Vr指充电中单体电池的电压上升过程中出现明显拐点的时刻对应的电压。示例性的，磷酸铁锂电池为例，最大电压Vr为3.4V。
S620、若单体电池的电压大于最大电压，则判断电池组需要均衡处理，根据单体电池的平均电压、单体电池的最低电压和电压预设浮动量获得第二基准电压，其中，当单体电池的电压大于第二基准电压时，则判断单体电池需要均衡处理。
示例性的，在充电结束工况进行均衡后，电池电压的一致性可逐步提高。此外，因为均衡时间是一个固定且保守的值，对于部分电池来说，可能均衡时间不够，这样电池电压的一致性不能够提高。为更好的提升均衡效果，在充电工况电池的电压差异较大的时候，采用基于电压差的均衡判断方式，当单体电池的电压大于最大电压Vr时，需要重新判断均衡的目标电池。第二基准电压是筛选目标电池的判断阈值，将平均电压和最低电压求和后做平均加上一定的电压预设浮动量作为第二基准电压，其中电压预设浮动量可以根据电池性能进行配置，例如：对于磷酸铁锂电池最大电压Vr为3.4V，充电过程中，如单体电池的电压大于3.4V，第二基准电压为（平均电压和最低电压）/2+20mV，则将单体电池的电压大于第二基准电压的电池判定为目标电池，均衡时间定为3分钟。因为充电工况电压变化较快，所以每3分钟后重新依据单体电池的电压差异判断目标电池。
基于上述实施例，示例性的，电池工况包括充电结束工况、充分静置工况、充电工况，其中，充分静置工况包括开路电压处于开路电压与电荷状态关系的线性变化区间内和开路电压处于开路电压与电荷状态关系的非线性变化区间内工况；
对目标电池进行电量均衡的优先级为所充电结束工况的优先级大于开路电压处于开路电压与电荷状态关系的线性变化区间内时的优先级；
开路电压处于开路电压与电荷状态关系的线性变化区间内时的优先级大于开路电压处于开路电压与电荷状态关系的非线性变化区间内时的优先级；
开路电压处于开路电压与电荷状态关系的非线性变化区间内时的优先级大于充电工况的优先级。
示例性的，电池组在应用中存在充电以及静置过程，因此电池组的运行工况至少包括充电结束工况、充分静置工况和充电工况中至少一种。因此，通过设定均衡优先级，在多种工况下执行高优先级的均衡时，低优先级的均衡过程需要等待高优先级均衡处理完毕之后才能够触发，从而提高电池均衡的灵活性，提高均衡效果。示例性的，在控制过程，均衡模式的初始为0，均衡模式1表示开路电压处于开路电压与电荷状态关系的非线性变化区间内时的均衡，均衡模式2表示开路电压处于开路电压与电荷状态关系的非线性变化区间内时的均衡，均衡模式3表示充电结束工况的均衡。充电工况的均衡模式保存在存储中，均衡模式的值越大代表优先级越高，只有当优先级高的均衡模式的待均衡时间变为0后，才能够触发低优先级的均衡模式。
示例性的，对目标电池进行电量均衡的过程中，包括：
获取单体电池的均衡温度，若均衡温度大于预设温度上限，则降低均衡电流；若均衡温度小于预设温度下限，则恢复均衡电流。
示例性的，设定预设温度上限和预设温度下限，在均衡过程采集单体电池的温度，即均衡温度，当最高的均衡温度大于或等于预设温度上限时，例如80℃，通过降低等效的均衡电流，以降低均衡温度。例如，均衡开启指令和均衡停止指令交替执行，因此均衡有效电流相当于降低为二分之一，以此降低均衡温度。当最高的均衡温度小于预设下限温度时，恢复均衡电流，保持均衡开启指令，一直执行均衡过程。
图7为本申请实施例提供一种电池组的电池均衡控制系统的结构示意图，参见图7，包括：
获取模块110，设置于获取电池组中的单体电池的电池状态；
工况确定模块120，设置于根据电池状态确定单体电池的电池工况；
判断模块130，设置于根据电池工况对电池组是否需要均衡进行判断，若判断电池组需要均衡处理，则根据电池状态和电池工况确定电池组中需均衡的目标电池；
均衡模块140，设置于对目标电池进行电量均衡。
示例性的，获取模块110获取电池组中的单体电池的电池状态，工况确定模块120通过单体电池的电池状态确定电池组的当前电池工况，针对不同的电池工况条件，判断模块对电池组进行均衡判断，若符合均衡要求，根据电池状态和电池工况确定电池组中需均衡的目标电池，均衡模块130从而对目标电池进行电量均衡，其中，判断模块140依据电池工况，进行判断并选择目标电池，避免了单一的运行工况下进行均衡判断带来的条件限制，提高了电量均衡的灵活性，提升了电池组一致性，提升电池组的可用容量和可用能量。
图8为本申请实施例提供一种电池管理系统的结构示意图，参见图8，包括：串联连接的单体电池组成的电池簇810、一级主控模块(Management Battery Management Unit，MBMU)、二级主控模块(Second Battery Management Unit，SBMU)、电压从控模块(Battery Management Unit，VCMU)、温度采集从板（Battery Temperature Unit，TCMU）、高压采集板（High-Voltage Management Unit，HMU）和显控 ( Human interface，HMI)组成。其中，需要说明的是，电池簇810的个数可以根据储能要求进行扩展配置，实现高压电池系统的管理。
电池管理系统中参与均衡控制的包括SBMU和集成了均衡模块的VCMU。其中，工况确定模块和判断模块相应的功能集成在SBMU中，均衡策略主要由SBMU进行判断均衡、启动和停止均衡的操作，SBMU向VCMU发送相应的启动或停止均衡命令，由VCMU根据SBMU的控制命令控制均衡硬件的开闭，执行单体电池的均衡过程。均衡命令通过CAN通信实现，发送采用周期方式发送，SBMU周期发送均衡命令给VCMU，VCMU收到均衡命令后，启动或关闭均衡硬件，并把均衡执行状态通过CAN总线发送出来。VCMU和TCMU对单体电池的电压、温度和电流等参数进行采集，其中，获取模块和均衡模块等功能的实现可以集成在VCMU内。
电池管理系统具有丰富的外部接口，能够满足多种场合的应用需求，这些接口包括：电压采集输入接口、温度采集输入接口、风扇控制输出接口、风扇信号反馈输入接口、加热控制输出接口、CAN2.0接口、以太网接口、RS485接口、干接点输出接口，开关量输入/输出接口，电流高速采集输入接口、高压信号采集输入接口。
图9为本申请实施例提供又一种均衡控制方法的流程示意图，参见图9，S710、每经过预设时间进行控制入口调用，示例性的，每200ms调用1次，开始执行；S720、获取均衡控制的相关故障信息，例如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障和存储故障等信息。S730、判断是否满足充分静置工况，若满足则S740、标记按照电池充分静置工况判断均衡。若不满足则跳过S740。
S750、判断是否满足充电结束后工况，若满足则S760、标记按照充电结束后工况判断均衡。若不满足则跳过S760。
S770、判断是否满足充电结束工况，若满足则S780、标记按照充电结束后工况判断均衡。若不满足则跳过S780。
S790、判断标记的各工况的电池是否满足均衡条件，其中，充分静置工况判断均衡条件为：电池管理系统无禁止均衡相关的故障，例如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障、EE故障等、电池温度≥45℃、均衡温度≥100℃。SBMU接收的各单体电池的电压累加总压和检测的总压差异小于10V。最低单体电压大于允许充分静置判断均衡电压阀值下限（如3.1V）。无高优先级的均衡模式。若SBMU判断以上条件满足，则触发一次充分静置判断均衡，即S800调用判断函数选择目标电池，S810、均衡执行。SBMU依据电池单体电压、最低电压、平均电压、OCV-SOC表等，判断需要均衡的电池和相应的均衡时间，均衡时间保存到存储中进行调用。
充电结束后工况判断均衡条件为：电池管理系统无禁止均衡相关的故障例如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障、存储故障等、电池温度≥45℃、均衡温度≥100℃。最低单体电压大于允许判断均衡电压阀值（如3.1V）。电流小于0.35C，且单体电池的最大电压保持大于Vr（如3.4V）持续1分钟以上。每3分钟判断以上条件是否满足，满足的话触发一次充电结束后工况判断均衡。即S800调用判断函数选择目标电池，判断单体电池电压高于（平均电压+最低电压）/2+预设的浮动量（可配置，如配置为20mV）的电池需要均衡，S810、均衡执行。均衡时间固定为3分钟，该时间不保存到存储中。
充电结束工况判断均衡条件为：电池管理系统无禁止均衡相关的故障例如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障、通信故障等、电池温度≥45℃、均衡温度≥100℃。单体电池的最低电压大于允许判断均衡电压阀值（如3.1V）。SBMU判断以上条件是否满足，若满足的触发一次充电结束工况判断均衡，即S800调用判断函数选择目标电池。SBMU依据电池最高电压、最低电压、平均电压、VH、VL1、VL2、VL3等，判断需要均衡的电池，S810、均衡执行，根据相应的均衡时间执行均衡，均衡时间保存到存储中，同时均衡模式置为3。
若S790不满足条件，则S820判断是否满足启动均衡的条件，例如如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障、存储故障、电池温度≥45℃和均衡温度≥100℃等，并且最低单体电压大于允许开启均衡电压阀值（如3.1V），则说明满足启动条件，则S830调用启动函数进行启动操作。
若S820不满足条件则S840、判断是否满足停止均衡条件，其中，满足停止均衡条件包括电池管理系统有禁止均衡相关的故障，例如单体电压检测故障、温度检测故障电流检测故障、V-CAN通信故障和存储故障等，以及电池温度≥45℃、均衡温度≥100℃等。最低电压小于或等于停止均衡电压阀值（如3.08V），满足以上任一条件时，SBMU将停止所有电池的均衡。
若SBMU开启均衡以后，需要对均衡时间进行计时，当某节单体电池需要均衡的时间均衡完成后，需要清除该节电池的均衡标志。当所有电池的均衡时间都完成以后，均衡停止，当存在以上任意情形时，S850调用停止均衡函数。
另外，为了防止电池搁置过久导致之前判断的均衡时间不再可信，S850在判断满足BMS上次下电时间和本次上电时间间隔超过240小时，且电池管理系统无禁止均衡相关的故障，SBMU收到各电芯电压后累加的总压和检测的总压差异小于10V时会标记需要清除均衡，S870调用清除均衡函数，清除掉存储的均衡时间。
图10为本申请实施例提供一种均衡判断的流程示意图，参见图10，其中，包括充电结束工况、电池充分静置工况和充电结束后工况的判断流程，方法步骤包括：
S900、判断均衡函数入口，S901、停止均衡，S910、判断是否为充电结束工况，若为充电结束工况则S920、清除均衡标记、均衡模式和均衡时间，S930、判断单体电池的最大电压是否小于第一阈值电压VL1，如3.5V，若最大电压小于第一阈值电压VL1，则说明所有单体电池的电压都小于第一阈值电压VL1，则说明电压均达不到要求，此时单体电池均不需要进行均衡。若最大电压大于第一阈值电压VL1，则S940、判断单体电池的最小电压是否小于第一阈值电压VL1，如3.5V，若最小电压小于第一阈值电压VL1，则S950、判断单体电池的最小电压是否小于第三阈值电压VL2，如3.45V，若最小电压大于第三阈值电压VL2，则S960、判断平均电压小于第一阈值电压VL1，若此时平均电压小于第一阈值电压VL1，则S970、说明电压低的单体电池较多，对电压高于第二阈值电压 VH的单体电池选取较长的均衡时间，例如，均衡时间定为0.7%电池实际容量对应的均衡时间。
若此时平均电压大于第一阈值电压VL1，则S980、说明电压低的单体电池较少，因此需要对电压高于第二阈值电压 VH的目标电池进行较短时间的放电均衡，例如均衡时间定为0.5%电池实际容量对应的均衡时间，S990、更新各电池的均衡标记和均衡时间，均衡模式设置为均衡模式3，S1001、保存均衡时间和均衡模式。
若最小电压小于第三阈值电压VL2，则S1002、判断单体电池的最小电压是否小于第四阈值电压VL3，如3.39V，若最小电压大于第三阈值电压VL2，S1003、对电压高于第一阈值电压VL1的电池的均衡时间定为1%电池实际容量对应的均衡时间，若最小电压小于第三阈值电压VL2，S1004、对电压高于第一阈值电压VL1的电池的均衡时间定为2%电池实际容量对应的均衡时间。
若判断不为充电结束工况，S1005、判断是否为电池充分静置工况，当前的均衡模式优先级是否小于均衡模式3。若为电池充分静置工况，S1006、清除均衡标记，S1007、计算基准容量阈值和第一基准电压，S1008、判断开路电压是否处于线性区间，若在线性区间内，则S1009、计算每个单体电池的电池容量与基准容量阈值的差异，将电池容量高于基准容量阈值的电池进行放电均衡，示例性的，为了保证不被过度均衡，可以将基准容量阈值加上单体电池当前的实际容量预设倍数的容量，作为浮动量进行判断，例如，将电池容量高于基准容量阈值+1.5%*当前的实际容量判断为目标电池。其中，预设倍数可以根据实际应用选择调整。后续均衡中，电池需要均衡放电容量为该单体电池当前的电池容量-基准容量阈值。S1010、更新各单体电池均衡标记和均衡时间，均衡模式设置为均衡模式2。S1011、保存均衡时间和均衡模式。
若开路电压在非线性区间内，则S1012、判断当前均衡模式优先级是否低于均衡模式2，若是则S1013、各单体电池的电压和第一基准电压的差异超过配置值，且单体电池的电压-第一基准电压≥30mv，则该电芯均衡20小时；如果单体电池的电压-第一基准电压≥15mv，则该电芯均衡10小时。S1014、更新各单体电池均衡标记和均衡时间，均衡模式设置为均衡模式1，S1011、保存均衡时间和均衡模式。
若判断不为电池充分静置工况，S1015、判断是否为充电结束后工况，若是S1016、清除均衡标记，S1017、计算第二基准电压，S1018、各单体电池的电压和第二基准电压的差异超过配置值的单体电池标记为需要均衡的单体电池。S1019、均衡时间定为3分钟。
图11为本申请实施例提供一种处理均衡判断的流程示意图，参见图11，S1100、处理均衡入口，S1101、判断均衡是否为开启状态，若为开启状态，S1102、充电结束后工况按压差均衡的时间是否大于零，若是S1103、充电结束后工况按压差均衡的时间减200ms，S1104、充电结束后工况按压差均衡的时间是否为零，若否则返回S1102。若是S1105、清除各电池的均衡标志，停止压差均衡。S1106、判断是否更新均衡标志使能或更新均衡时间，若是则S1107、根据均衡时间更新均衡标志，S1108，判断剩余均衡时间是否不为零，若是则S1109启动均衡，S1110判断电池的最高均衡温度是否大于或等于80℃，若大于或等于80℃则S1111、降低等效均衡电流。若小于80℃则S1112、判断电池的最高均衡温度是否小于70℃，若小于70℃则S1113、等效均衡电流恢复正常。S1114、判断当前均衡状态为关闭或到达关闭30S均衡时间，若是则S1115、关闭所有电池的均衡指令。如否则S1116根据均衡标志发送启动或关闭电池均衡指令。
图12为本申请实施例提供一种均衡模块的电路结构示意图，图13为本申请实施例提供一种均衡支路结构示意图，参见图12和图13，包括：控制单元220和多个均衡支路210，每一均衡支路210与一单体电池连接。
其中，控制单元可以包括ADBMS6815电池管理芯片，电阻R1、电阻R2、电阻R4、电阻R5是NTC温度测量的分压电阻，通过采集电阻R1上的分压大小计算当前温度条件下的电阻值，通过查找项目所采用的NTC传感器的R-T表，可找到对应该阻值下的温度值。
均衡有效电流要求应≥60mA@3.2V，3.2V除以0.06A，计算对应的均衡电阻不能超过53Ω。由于电压采集采用电压测量时自动关闭均衡功能，均衡最大有效利用率一般在90%，53Ω*90%，得出均衡电阻需要控制在47.7Ω以下。考虑一定预留和电阻精度因素，方案设计实际设计为39Ω，按最高均衡电压Uc=4.2V，计算均衡电阻功率P=4.2*4.2/39=0.45W，电阻功率选用1.5W。查电阻降额曲线，85℃环境温度下，电阻降额率在80%。对应的可用功率为：1.5W*0.8=1.2W。因此85℃环境下，均衡电阻最大工作功率是电阻的额定功率：0.45W/1.2W=37.5%。功率选型预留足够，满足设计要求。均衡支路的均衡过程：
通过电子开关Q1的闭合和断开来控制均衡电路的启动与停止。示例性的，电子开关Q1可以采用NMOS开关，在均衡开始时，控制单元输出控制信号至电子开关Q1的控制端1，电子开关Q1的第一端2和第二端3导通，单体的电池正BAT01_01的电压经过电阻R2、电阻R3、电阻R4、电子开关Q1至电池负，实现均衡放电过程。在均衡结束时，控制单元输出控制信号截止电子开关Q1。相同的其他组电池，以此类推，实现各单体电池的均衡放电控制。

Claims (15)

  1. 一种电池组的电量均衡方法，包括：
    获取电池组中的单体电池的电池状态；
    根据所述电池状态确定所述单体电池的电池工况；
    根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
    对所述目标电池进行电量均衡。
  2. 根据权利要求1所述的电池组的电量均衡方法，其中，所述电池工况包括充电结束工况；根据所述电池工况对所述电池组是否需要均衡进行判断，包括：
    根据所述单体电池确定第一阈值电压和第二阈值电压；其中，所述第一阈值电压小于第二阈值电压；
    获取所述电池组中每一所述单体电池的电压；以及
    根据所述单体电池的电压、所述第一阈值电压和所述第二阈值电压之间的关系对所述电池组进行均衡判断；其中，若至少部分所述单体电池的所述电压小于所述第一阈值电压，且至少部分所述单体电池的所述电压大于所述第二阈值电压，则判断所述电池组需要均衡处理。
  3. 根据权利要求2所述的电池组的电量均衡方法，其中，根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池，包括：
    根据所述单体电池确定第三阈值电压，其中，所述第三阈值电压小于所述第一阈值电压；
    根据所述单体电池的最低电压、所述第一阈值电压、所述第二阈值电压、和所述第三阈值电压确定目标电池；其中，若所述单体电池的最低电压大于或等于所述第三阈值电压，则标记所述电压大于所述第二阈值电压的所述单体电池为所述目标电池；以及
    若所述单体电池的最低电压小于所述第三阈值电压，则标记所述电压大于所述第一阈值电压的所述单体电池为所述目标电池。
  4. 根据权利要求3所述的电池组的电量均衡方法，其中，所述第一阈值电压为充电结束时刻所述单体电池的电压达到第一预设电荷状态对应的电压值；所述第二阈值电压为充电结束时刻所述单体电池的电压达到第二预设电荷状态对应的电压值；所述第三阈值电压为充电结束时刻所述单体电池的电压达到第三预设电荷状态对应的电压值；其中，所述第二预设电荷状态大于所述第一预设电荷状态；所述第一预设电荷状态大于所述第三预设电荷状态。
  5. 根据权利要求4所述的电池组的电量均衡方法，其中，根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池，包括：
    根据所述单体电池确定第四阈值电压，其中，所述第四阈值电压小于所述第三阈值电压；
    根据所述单体电池的最低电压、所述第一阈值电压、所述第二阈值电压、所述第三阈值电压和所述第四阈值电压确定目标电池；其中，若所述单体电池的最低电压小于所述第三阈值电压，且大于或等于所述第四阈值电压，则标记所述电压大于所述第一阈值电压的所述单体电池为所述目标电池；以及
    若所述单体电池的最低电压小于所述第四阈值电压，则标记所述电压大于所述第一阈值电压的所述单体电池为所述目标电池。
  6. 根据权利要求1至4任一项所述的电池组的电量均衡方法，其中，所述电池工况包括充分静置工况；根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池，包括：
    当所述单体电池充分静置后的开路电压处于开路电压与电荷状态关系的线性变化区间内时，获取所述单体电池的电池容量和所述单体电池的平均容量；
    根据所述电池容量和所述平均容量确定基准容量阈值；以及
    根据所述电池容量和所述基准容量阈值确定所述目标电池，其中，若所述电池容量大于所述基准容量阈值，则标记所述单体电池为所述目标电池。
  7. 根据权利要求6所述的电池组的电量均衡方法，其中，若所述电池容量大于所述基准容量阈值加上所述单体电池当前的实际容量预设倍数的容量，则标记所述单体电池为所述目标电池。
  8. 根据权利要求6所述的电池组的电量均衡方法，其中，根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池，还包括：
    当所述开路电压处于开路电压与电荷状态关系的非线性变化区间内时，获取所述单体电池的电压、所述单体电池的平均电压和所述单体电池的最低电压；
    根据所述单体电池的平均电压和所述单体电池的最低电压确定第一基准电压；以及
    根据所述单体电池的电压和所述第一基准电压确定所述目标电池，其中，若所述单体电池的电压和所述第一基准电压的差值大于均衡预设值，则标记所述单体电池为所述目标电池。
  9. 根据权利要求8所述的电池组的电量均衡方法，其中，若所述单体电池的电压与第一基准电压的差值大于或等于预设差值，则判断所述单体电池为所述目标电池通过设置不同的预设差值，对应设置所述目标电池的均衡电量或均衡时间。
  10. 根据权利要求1至4任一项所述的电池组的电量均衡方法，其中，所述电池工况包括充电工况；若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池，包括：
    获取所述单体电池的电压、所述单体电池的平均电压、所述单体电池的最低电压和所述单体电池充电过程的最大电压；
    若所述单体电池的电压大于所述最大电压，则判断所述电池组需要均衡处理；以及
    根据所述单体电池的平均电压、所述单体电池的最低电压和电压预设浮动量获得第二基准电压，当所述单体电池的电压大于所述第二基准电压时，则标记所述单体电池为所述目标电池。
  11. 根据权利要求10所述的电池组的电量均衡方法，其中，所述第二基准电压是筛选所述目标电池的判断阈值，将平均电压和最低电压求和后做平均加上压预设浮动量作为所述第二基准电压。
  12. 根据权利要求1至4任一项所述的电池组的电量均衡方法，其中，所述电池工况包括充电结束工况、充分静置工况和充电工况，其中，所述充分静置工况包括开路电压处于开路电压与电荷状态关系的线性变化区间内和所述开路电压处于所述开路电压与电荷状态关系的非线性变化区间内工况；
    对所述目标电池进行电量均衡的优先级为：所述充电结束工况的优先级大于所述开路电压处于所述开路电压与电荷状态关系的线性变化区间内时的优先级；
    所述开路电压处于所述开路电压与电荷状态关系的线性变化区间内时的优先级大于所述开路电压处于所述开路电压与电荷状态关系的非线性变化区间内时的优先级；
    所述开路电压处于所述开路电压与电荷状态关系的非线性变化区间内时的优先级大于所述充电工况的优先级。
  13. 根据权利要求1至4任一项所述的电池组的电量均衡方法，其中，对所述目标电池进行电量均衡的过程中，包括：
    获取所述单体电池的均衡温度，若所述均衡温度大于预设温度上限，则降低均衡电流；以及
    若所述均衡温度小于预设温度下限，则恢复所述均衡电流。
  14. 一种电池组的电池均衡控制系统，包括：
    获取模块，设置于获取电池组中的单体电池的电池状态；
    工况确定模块，设置于根据所述电池状态确定所述单体电池的电池工况；
    判断模块，设置于根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
    均衡模块，设置于对所述目标电池进行电量均衡。
  15. 一种电池管理系统，包括电池组的电池均衡控制系统，其中，所述电池组的电池均衡控制系统包括：
    获取模块，设置于获取电池组中的单体电池的电池状态；
    工况确定模块，设置于根据所述电池状态确定所述单体电池的电池工况；
    判断模块，设置于根据所述电池工况对所述电池组是否需要均衡进行判断，若判断所述电池组需要均衡处理，则根据所述电池状态和所述电池工况确定所述电池组中需均衡的目标电池；以及
    均衡模块，设置于对所述目标电池进行电量均衡；
    所述电池管理系统包括：二级主控模块、电压从控模块和温度采集从板；
    其中，所述工况确定模块和所述判断模块集成于所述二级主控模块中，所述获取模块集成于所述电压从控模块和所述温度采集从板中，所述均衡模块集成于所述电压从控模块中。
PCT/CN2022/144106 2022-10-26 2022-12-30 电池组的电量均衡方法及系统、电池管理系统 WO2024087386A1 (zh)

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