A vehicle battery equalization method and system

Abstract

The present invention relates to a vehicle battery equalization method and system, wherein the method comprises: when the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, judging whether the current battery inspection moment satisfies the conditions for starting battery equalization judgment, and if so, determining the first battery cell that needs to be equalized in the vehicle battery and the corresponding first equalization time; after the vehicle is powered on, obtaining the vehicle's operating condition, and if the vehicle's operating condition is a driving condition, performing driving equalization on the first battery cell according to the first equalization time. The method improves the accuracy of fault judgment, reduces the possibility of false alarm faults, and does not require additional hardware costs.

Description

Technical Field

[0001] The present invention relates to the field of battery balancing, and in particular to a vehicle battery balancing method and system. Background Art

[0002] Power batteries are an indispensable component of new energy vehicles, and battery life is one of the core issues in power battery applications. Due to differences in manufacturing, use environment, etc., the differences in battery cells continue to increase during use. If not controlled, the battery life will also decline rapidly. As the control unit of the power battery, the battery management system (BMS) undoubtedly needs to assume the important function of balancing the power battery.

[0003] Existing balancing solutions include balancing during charging and balancing at power-on. During charging, balancing is performed at the end of charging when the battery status is relatively stable. It is possible to determine the battery cells that need to be balanced and balance them to ensure the consistency of the battery pack and increase the amount of power charged. Due to the current increase in charging power, the charging time of this method is shortened. For batteries with larger capacities, the balancing time cannot meet the requirements. Balancing at power-on determines the cell status at the moment of power-on, identifies the battery cells that need to be balanced, and performs balancing. This method cannot determine the static time experienced by the battery, and there is a certain error in the determination of the balancing result. It can be seen that the existing battery balancing solutions have the defects of inaccurate balancing judgment or the balancing time cannot meet the requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a vehicle battery equalization method and system to solve the defects of the battery equalization scheme in the prior art, that is, the equalization judgment is not accurate enough and the equalization time cannot meet the requirements.

[0005] To achieve the above object, a first aspect of the present invention provides a vehicle battery equalization method, comprising the following steps:

[0006] When the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, determining whether the current battery inspection time satisfies the condition for starting battery balancing judgment, and if so, determining the first battery cell that needs to be balanced in the vehicle battery and the corresponding first balancing time;

[0007] After the vehicle is powered on, the operating condition of the vehicle is obtained. If the operating condition of the vehicle is a driving condition, driving balancing is performed on the first battery cell according to the first balancing time.

[0008] Preferably, the determining whether the current battery inspection time satisfies the conditions for starting battery balancing determination specifically includes:

[0009] Determining the type of battery cells in the vehicle battery and the ambient temperature thereof, and determining the static time of the battery cells according to the type of the battery cells and the ambient temperature;

[0010] The interval between the current battery inspection time and the vehicle power-off time is calculated to determine whether the interval is greater than the static time. If so, it is determined that the current battery inspection time meets the condition for starting battery balancing judgment, otherwise the condition is not met.

[0011] Preferably, the determining of the first balancing time corresponding to the first battery cell that needs to be balanced in the vehicle battery specifically includes:

[0012] Obtaining an SOC difference value of the first battery cell according to a voltage value of the first battery cell, an average voltage value of the battery cell, and an average temperature value of a battery patrol measurement point;

[0013] A first balancing time corresponding to the first battery cell is obtained by calculation according to the capacity value of the first battery cell, the SOC difference, and a first balancing current value corresponding to the first battery cell.

[0014] Preferably, if the operating condition of the vehicle is a driving condition, performing driving balancing on the first battery cell according to the first balancing time specifically includes:

[0015] Driving balancing is performed on the first battery cell according to the first balancing time and the first balancing current. If it is detected that the operating condition of the vehicle is switched from the driving condition to the charging condition during the driving balancing, a second battery cell that needs to be balanced in the vehicle battery is re-determined, and charging balancing is performed on the second battery cell.

[0016] Preferably, performing charge balancing on the second battery cell specifically includes:

[0017] The second battery cell is charged and balanced according to the set balancing method. During the charging and balancing process, if it is detected that the charging current is less than the set current value and lasts for a set time, the current voltage value of the second battery cell is obtained, and the SOC value of the second battery cell is determined according to the current voltage value. The second balancing time of the second battery cell is calculated according to the capacity value of the second battery cell, the SOC value of the second battery cell and the second balancing current value of the battery cell in charging and balancing, and the second balancing time is saved.

[0018] Preferably, the method further comprises:

[0019] When the charge equalization is completed, if it is detected that the driving condition of the vehicle is switched to the driving condition, driving equalization is performed on the second battery cell according to the second equalization time and the second equalization current.

[0020] Preferably, if the operating condition of the vehicle is a driving condition, performing driving balancing on the first battery cell according to the first balancing time specifically includes:

[0021] During the process of performing the driving balancing on the first battery cell, if it is detected that the operating condition of the vehicle has not switched, the difference between the first balancing time and the driving balancing execution time is calculated to obtain the remaining balancing time, and the first balancing time is updated with the remaining balancing time.

[0022] Preferably, the method further comprises:

[0023] If the driving condition of the vehicle is determined to be a charging condition, the third battery cell that needs to be balanced in the vehicle battery is re-determined, and the third battery cell is charged and balanced according to the set balancing method. If, during the process of charging and balancing the third battery cell, the charging current is less than the set charging current and lasts for a set time, the current voltage value of the third battery cell is obtained, the SOC value of the third battery cell is determined according to the current voltage value of the third battery cell, the third balancing time of the third battery cell is determined according to the capacity value of the third battery cell, the SOC value of the third battery cell and the third balancing current value corresponding to the third battery cell, and the third balancing time is saved.

[0024] Preferably, the method further comprises:

[0025] After the charge equalization is performed, if the operating condition of the vehicle is switched to a driving condition, driving equalization is performed on the third battery cell according to the third equalization time and the third equalization current.

[0026] A second aspect of the present invention provides a vehicle battery balancing system, comprising:

[0027] A battery balancing determination unit, configured to determine whether a current battery inspection time satisfies a condition for starting battery balancing determination when the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, and if so, determine a first battery cell in the vehicle battery that needs to be balanced and a corresponding first balancing time;

[0028] a control unit, configured to obtain the operating condition of the vehicle after the vehicle is powered on, and if the operating condition of the vehicle is a driving condition, perform driving balancing on the first battery cell according to the first balancing time;

[0029] The beneficial effects of the present invention are as follows: after the vehicle is powered off, the battery management system determines the battery cells that need to be balanced and the corresponding balancing time during the inspection phase. After the vehicle is powered on, if the vehicle is in driving condition, the balancing is performed according to the determined balancing time. This method is based on battery characteristics and uses the inspection working opportunity to accurately find the battery steady state, update the balancing time, and continuously perform balancing according to the balancing time during driving, ensuring sufficient balancing time. In addition, when the vehicle is in charging condition, the charging steady state is also used for balancing and updating the balancing time. This method improves the accuracy of fault judgment, reduces the possibility of false alarm faults, and does not require additional hardware costs.

[0030] Other features and advantages of the embodiments of the present invention will be further described in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic flow chart of a vehicle battery equalization method according to a first embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of a battery management system inspection according to Embodiment 1 of the present invention;

[0034] Figure 3 Another schematic diagram of the vehicle battery equalization method according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0035] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. In addition, in order to better illustrate the present invention, numerous specific details are provided in the specific embodiments below. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details. In some instances, means well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0036] Embodiment 1 of the present invention proposes a vehicle battery equalization method, which is combined with Figure 1-3 The method comprises the following steps:

[0037] S1. When the vehicle is in a power-off state, determine whether the battery management system of the vehicle is in a battery inspection state. If in the battery inspection state, determine whether the current battery inspection time satisfies the condition for starting battery balancing judgment. If so, determine the first battery cell that needs to be balanced in the vehicle battery and the corresponding first balancing time. If not in the battery inspection state, use the balancing time determined when the vehicle ends its use as the first balancing time.

[0038] The vehicle's BMS has a wake-up source, and the working state of the wake-up source is related to whether the BMS is in the battery inspection state. Generally, whether the vehicle's BMS is in the battery inspection state can be determined by the working state of the wake-up source. Figure 2 As shown, during the period of BMS sleep, the BMS wakes up regularly at regular intervals and detects the battery status.

[0039] If the BMS is in the battery inspection state, determine whether the current time meets the time requirement for starting battery balancing judgment based on the vehicle power-off time, the current battery inspection time, and the static time of the battery cell. If it does, obtain the battery cell voltage value detected by the battery inspection, and determine the first battery cell that needs to be balanced and the corresponding first balancing time based on the battery cell voltage value. If the BMS is not in the inspection state, use the remaining balancing time at the end of vehicle use as the first balancing time.

[0040] Specifically, when the battery management system of the vehicle starts the battery inspection function for the vehicle battery and is in the battery inspection state, the current battery inspection time is obtained, the type of battery cell and the ambient temperature of the battery cell are determined, the static time of the battery cell is determined according to the type of battery cell and the ambient temperature of the battery cell, and the interval between the power-off time of the vehicle and the current battery inspection time is calculated. If the interval is longer than the static time of the battery cell, it is determined that the current battery inspection time meets the conditions for starting the battery equalization judgment. Otherwise, it is considered that the current battery inspection time does not meet the conditions for starting the battery equalization judgment. If the conditions for starting the battery equalization judgment are not met, it continues to wait for the next inspection to determine whether the next inspection time meets the conditions for starting the battery equalization judgment. For example, the static time of the nickel-cobalt-manganese ternary lithium battery is 1 hour in summer and 2 hours in winter. That is, in summer, if the battery cell is a nickel-cobalt-manganese ternary lithium battery, the time between the vehicle power-off time and the current battery inspection time should be greater than 1 hour to be considered to meet the conditions for starting battery balancing judgment. If the conditions are met, the battery cell that needs to be balanced is determined and the corresponding first balancing time is calculated. Otherwise, the inspection continues until the static time requirement is met.

[0041] Specifically, the average voltage value of the battery cells in the battery module is calculated to determine whether the voltage value of the battery cell is greater than the average voltage value. If it is greater than the average voltage value, it means that the battery cell needs to be balanced, that is, the first battery cell. Otherwise, no balancing is required.

[0042] Specifically, the voltage value of the first battery cell during the current battery inspection and the average voltage value of the battery cells of the battery module are obtained, and the average temperature value of multiple measuring points during the battery inspection is calculated, and the first battery cell voltage value, the average voltage value of the battery cell and the average temperature value are used to query the OCV table to obtain the SOC difference of the first battery cell, and the product of the SOC difference of the first battery cell and the capacity of the first battery cell is calculated, and the product is divided by the first balancing current value corresponding to the first battery cell to obtain the first balancing time, and the first balancing time is saved.

[0043] S2. After the vehicle is powered on, the operating condition of the vehicle is obtained. If the operating condition of the vehicle is a driving condition, driving balancing is performed on the first battery cell according to the first balancing time. Before the vehicle ends use, the remaining balancing time is calculated and saved.

[0044] When the vehicle is powered on, the vehicle's operating condition is obtained. When the vehicle's operating condition is a driving condition, driving balancing is performed on the first battery cell according to the first balancing current and the first balancing time. When the vehicle is no longer in use, the balancing time is updated and saved.

[0045] It should be noted that there are two situations when executing driving balancing on the first battery cell. First, driving balancing has not been completed, and the vehicle's operating condition is switched from driving condition to charging condition. Second, during the process of executing driving balancing on the first battery cell, the vehicle's operating condition has not changed, that is, before the vehicle is finished using, the vehicle's operating condition is the driving condition.

[0046] If the vehicle's operating conditions do not change during the execution of driving balancing, that is, the vehicle's driving conditions remain until the end of its use, the difference between the first balancing time and the executed driving balancing time is calculated to obtain the remaining balancing time, and the first balancing time is updated with the remaining balancing time, and then the vehicle's use ends.

[0047] For example, assuming that the first balancing time is 40 minutes, after the vehicle is powered on, the vehicle's operating condition has always been the driving condition. If the vehicle's driving condition continues for 30 minutes and the vehicle stops driving, the calculated remaining balancing time is 10 minutes. The balancing time is updated to 10 minutes and saved.

[0048] During the process of executing driving balancing, if the vehicle's operating condition is switched from the driving condition to the charging condition, when the vehicle's operating condition is the charging condition, the second battery cell that needs to be balanced in the vehicle battery is re-determined, and charging balancing is performed on the second battery cell according to the set battery balancing method. During the process of executing charging balancing, if the charging current is less than the set current value and lasts for a set time, the current voltage value of the second battery cell is obtained, and the SOC difference of the second battery cell is determined according to the current voltage value of the second battery cell and the average voltage value of the battery cell. The second balancing time of the second battery cell is calculated according to the capacity of the second battery cell, the SOC difference of the second battery cell and the second balancing current corresponding to the second battery cell, and the balancing time of the second battery cell is updated with the second balancing time. When the vehicle is used, the balancing time is updated and saved.

[0049] If the vehicle's operating condition is switched to a driving condition after the second battery cell is charged and balanced, the second battery cell is balanced according to the second balancing time and the second balancing current corresponding to the second battery cell. The driving balancing of the second battery cell according to the second balancing time and the second balancing current is the same as the driving balancing of the first battery cell according to the first balancing time and the first balancing current.

[0050] The set current value is 0.1C, the set time is preferably 30 minutes, and the set balancing mode may be a voltage balancing mode.

[0051] After the vehicle is powered on, if the vehicle is in a charging condition, the third battery cell that needs to be balanced in the vehicle battery is determined by charging, and charging and balancing are performed on the third battery cell according to a set balancing method. During the charging and balancing process, if the charging current is less than a set current value and lasts for a set time, the current voltage value of the third battery cell is obtained, and the SOC difference of the third battery cell is determined according to the current voltage value of the third battery cell and the average voltage value of the battery cell. A third balancing time of the third battery cell is obtained according to the capacity of the third battery cell, the SOC difference of the third battery cell and a third balancing current corresponding to the third battery cell, and the balancing time of the third battery cell is updated with the third balancing time, and the third balancing time is saved. Then, the use of the vehicle ends.

[0052] If the vehicle's operating condition is switched to a driving condition after the third battery cell is charged and balanced, driving balance is performed on the third battery cell according to the third balancing time and the third balancing current corresponding to the third battery cell. The driving balance performed on the third battery cell according to the third balancing time and the third balancing current is the same as the driving balance performed on the first battery cell according to the first balancing time and the first balancing current.

[0053] The vehicle battery balancing method of the embodiment of the present invention determines the battery cells that need to be balanced and the corresponding balancing time during the inspection phase of the battery management system after the vehicle is powered off, and performs balancing according to the determined balancing time when the vehicle is in driving condition after the vehicle is powered on. The method is based on battery characteristics and uses the inspection working opportunity to accurately find the battery steady state, update the balancing time, and continuously perform balancing according to the balancing time during driving, ensuring sufficient balancing time. In addition, when the vehicle is in charging condition, the charging steady state is also used to perform balancing and update the balancing time. The method improves the accuracy of fault judgment, reduces the possibility of false alarm faults, and does not require additional hardware costs.

[0054] Based on the first embodiment of the present invention, the second embodiment of the present invention provides a vehicle battery balancing system, including a battery balancing determination unit and a control unit, wherein the battery balancing determination unit is used to determine whether the current battery inspection moment meets the conditions for starting battery balancing judgment when the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, and if so, determine the first battery cell that needs to be balanced in the vehicle battery and the corresponding first balancing time, and the control unit is used to obtain the operating condition of the vehicle after the vehicle is powered on, and if the operating condition of the vehicle is a driving condition, perform driving balancing on the first battery cell according to the first balancing time.

[0055] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A vehicle battery equalization method, characterized in that: include: When the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, determining whether the current battery inspection time satisfies the condition for starting battery balancing judgment, and if so, determining the first battery cell that needs to be balanced in the vehicle battery and the corresponding first balancing time; After the vehicle is powered on, obtaining a use condition of the vehicle, and if the use condition of the vehicle is a driving condition, performing driving balancing on the first battery cell according to the first balancing time; The determination of whether the current battery inspection time satisfies the conditions for starting battery balancing determination specifically includes: Determining the type of battery cells in the vehicle battery and the ambient temperature thereof, and determining the static time of the battery cells according to the type of the battery cells and the ambient temperature; The interval between the current battery inspection time and the vehicle power-off time is calculated to determine whether the interval is greater than the static time. If so, it is determined that the current battery inspection time meets the condition for starting battery balancing judgment, otherwise the condition is not met.

2. The method according to claim 1, characterized in that The step of determining a first balancing time corresponding to a first battery cell that needs to be balanced in the vehicle battery specifically includes: Obtaining an SOC difference value of the first battery cell according to a voltage value of the first battery cell, an average voltage value of the battery cell, and an average temperature value of a battery patrol measurement point; A first balancing time corresponding to the first battery cell is obtained by calculation according to the capacity value of the first battery cell, the SOC difference, and a first balancing current value corresponding to the first battery cell.

3. The method according to claim 2, characterized in that If the operating condition of the vehicle is a driving condition, performing driving balancing on the first battery cell according to the first balancing time specifically includes: Driving balancing is performed on the first battery cell according to the first balancing time and the first balancing current. If the operating condition of the vehicle is switched from a driving condition to a charging condition during the driving balancing, a second battery cell that needs to be balanced in the vehicle battery is re-determined, charging balancing is performed on the second battery cell, a remaining balancing time is calculated, and the remaining balancing time is saved.

4. The method according to claim 3, characterized in that The performing charge balancing on the second battery cell, calculating the remaining balancing time, and storing the remaining balancing time specifically includes: The second battery cell is charged and balanced according to the set balancing method. During the charging and balancing process, if it is detected that the charging current is less than the set current value and lasts for a set time, the current voltage value of the second battery cell is obtained, and the SOC value of the second battery cell is determined according to the current voltage value. The second balancing time of the second battery cell is calculated according to the capacity value of the second battery cell, the SOC value of the second battery cell and the second balancing current value of the battery cell in charging and balancing, and the second balancing time is saved.

5. The method according to claim 4, characterized in that The method further comprises: When the charge balancing is completed, if the driving condition of the vehicle is switched to a driving condition, driving balancing is performed on the second battery cell according to the second balancing time and the second balancing current.

6. The method according to claim 2, characterized in that If the operating condition of the vehicle is a driving condition, performing driving balancing on the first battery cell according to the first balancing time specifically includes: During the process of performing the driving balancing on the first battery cell, if it is detected that the operating condition of the vehicle has not switched, before the end of the use of the vehicle, the difference between the first balancing time and the driving balancing execution time is calculated to obtain the remaining balancing time, and the first balancing time is updated with the remaining balancing time.

7. The method according to claim 2, characterized in that The method further comprises: If the driving condition of the vehicle is determined to be a charging condition, the third battery cell that needs to be balanced in the vehicle battery is re-determined, and the third battery cell is charged and balanced according to the set balancing method. If, during the process of charging and balancing the third battery cell, the charging current is less than the set charging current and lasts for a set time, the current voltage value of the third battery cell is obtained, the SOC value of the third battery cell is determined according to the current voltage value of the third battery cell, the third balancing time of the third battery cell is determined according to the capacity value of the third battery cell, the SOC value of the third battery cell and the third balancing current value corresponding to the third battery cell, and the third balancing time is saved.

8. The method according to claim 7, characterized in that The method further comprises: After the charge equalization is performed, if the operating condition of the vehicle is switched to a driving condition, driving equalization is performed on the third battery cell according to the third equalization time and the third equalization current.

9. A vehicle battery equalization system, characterized in that: include: A battery balancing determination unit, configured to determine whether a current battery inspection time satisfies a condition for starting battery balancing determination when the vehicle is in a power-off state and the battery management system of the vehicle is in a battery inspection state, and if so, determine a first battery cell in the vehicle battery that needs to be balanced and a corresponding first balancing time; a control unit, configured to obtain a use condition of the vehicle after the vehicle is powered on, and if the use condition of the vehicle is a driving condition, perform driving balancing on the first battery cell according to the first balancing time; The determination of whether the current battery inspection time satisfies the conditions for starting battery balancing determination specifically includes: Determining the type of battery cells in the vehicle battery and the ambient temperature thereof, and determining the static time of the battery cells according to the type of the battery cells and the ambient temperature; The interval between the current battery inspection time and the vehicle power-off time is calculated to determine whether the interval is greater than the static time. If so, it is determined that the current battery inspection time meets the condition for starting battery balancing judgment, otherwise the condition is not met.

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