State of charge determination method, apparatus, medium, battery control system, and vehicle

Abstract

This disclosure relates to a method, apparatus, medium, battery control system, and vehicle for determining the state of charge (SOC). After a first charge transfer between a first sub-battery pack and a second sub-battery pack, a second charge transfer is performed between them to equalize the SOC of the first and second sub-battery packs. The SOC at which the SOC of the first and second sub-battery packs are equal is determined as the SOC of the power battery. This allows for a more accurate SOC determination of the power battery, providing accurate SOC at any stage of the power battery's charge, without requiring a battery model, thus reducing workload and saving time and resources.

Description

Technical Field

[0001] This disclosure relates to the field of battery management technology, and more specifically, to a method, apparatus, medium, battery control system, and vehicle for determining the state of charge. Background Technology

[0002] For electric vehicles, in order to avoid the vehicle breaking down while driving, users have an increasingly higher demand for accurate battery state of charge.

[0003] In related technologies, the open-circuit voltage method can be used to determine the state of charge of a battery. However, this method is very ineffective for lithium iron phosphate batteries. The method can only estimate the state of charge of a battery when the battery's state of charge is below 20% or above 95%.

[0004] The method for determining the state of charge of a battery using Kalman filtering requires the establishment of a reliable battery model, which involves a large amount of matching work and consumes a lot of time and resources. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method, apparatus, medium, battery control system, and vehicle for determining the state of charge (SOC). By dividing a power battery into a first sub-cell and a second sub-cell, and controlling a first charge transfer between the first and second sub-cells, followed by a second charge transfer, the SOC of the first and second sub-cells is made equal, thus obtaining the SOC of the power battery. This method provides a relatively accurate SOC for the power battery, applicable to any stage of its charge, without requiring a battery model, reducing workload and saving time and resources.

[0006] To achieve the above objectives, according to a first aspect of the present disclosure, a method for determining the state of charge is provided, applied to a power battery, the power battery including a first sub-battery pack and a second sub-battery pack, the method comprising:

[0007] After controlling the first power transfer between the first sub-battery pack and the second sub-battery pack, control the second power transfer between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal.

[0008] The state of charge (SOC) of the power battery is defined as the SOC when the SOC of the first sub-battery pack is equal to that of the second sub-battery pack.

[0009] Optionally, after controlling the first sub-battery pack and the second sub-battery pack to perform a first power transfer, controlling the first sub-battery pack and the second sub-battery pack to perform a second power transfer, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal, includes:

[0010] Control the first power transfer between the first sub-battery pack and the second sub-battery pack, and obtain the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack;

[0011] Based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, a second power transfer is controlled between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal.

[0012] Optionally, before performing a first power transfer between the first sub-battery pack and the second sub-battery pack, and obtaining a first state of charge of the first sub-battery pack and a second state of charge of the second sub-battery pack, the method further includes:

[0013] Obtain the voltage of a single cell in the power battery;

[0014] The control of the first power transfer between the first sub-battery pack and the second sub-battery pack includes:

[0015] When the voltage of a single cell in the power battery is within the target plateau range, the first power transfer is controlled between the first sub-battery pack and the second sub-battery pack.

[0016] Optionally, the step of controlling the first sub-battery pack and the second sub-battery pack to perform a first power transfer, and obtaining the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, includes:

[0017] Control the first power transfer between the first sub-battery pack and the second sub-battery pack so that the voltage of a single cell in the first sub-battery pack reaches the target voltage range;

[0018] When the voltage of a single cell in the first sub-battery pack reaches the target voltage range, the target voltage of the single cell in the first sub-battery pack, the first charge change value of the first sub-battery pack, and the second charge change value of the second sub-battery pack are obtained.

[0019] Based on the target voltage, the first state of charge of the first sub-battery pack is obtained;

[0020] The second state of charge of the second sub-battery pack is obtained based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery.

[0021] Optionally, obtaining the first power change value of the first sub-battery pack and the second power change value of the second sub-battery pack includes:

[0022] The first current of the first sub-battery pack during the first power transfer, the second current of the second sub-battery pack during the first power transfer, and the first duration of the first power transfer are obtained.

[0023] The product of the first current and the first duration is determined as the first change in charge of the first sub-battery pack, and the product of the second current and the first duration is determined as the second change in charge of the second sub-battery pack.

[0024] Optionally, obtaining the first state of charge of the first sub-battery pack based on the target voltage includes:

[0025] Based on the target voltage, the first state of charge is obtained according to the correspondence between the voltage of a single cell in the power battery and the state of charge of the power battery.

[0026] Optionally, obtaining the second state of charge of the second sub-battery pack based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery includes:

[0027] The initial state of charge of the first sub-battery pack is obtained based on the first state of charge, the first change in charge value, and the total capacity of the power battery.

[0028] The second state of charge is obtained based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery.

[0029] Optionally, the initial state of charge of the first sub-battery pack is obtained based on the first state of charge, the first change in charge value, and the total capacity of the power battery, including:

[0030] When the first sub-battery pack discharges, SOC 上部分初始 =SOC 上部分 +C1 / C0

[0031] When the first sub-battery pack is charging, SOC 上部分初始 =SOC 上部分 -C1 / C0

[0032] Among them, SOC 上部分初始The initial state of charge (SOC) of the first sub-cell pack. 上部分 C1 represents the first state of charge of the first sub-battery pack, C0 represents the first change in charge of the first sub-battery pack, and C0 represents the total capacity of the power battery.

[0033] Optionally, obtaining the second state of charge based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery includes:

[0034] When the second sub-battery pack is charging, the SOC 下部分 =SOC 上部分初始 +C2 / C0

[0035] When the second sub-cell pack discharges, SOC 下部分 =SOC 上部分初始 -C2 / C0

[0036] Among them, SOC 下部分 The second state of charge (SOC) of the second sub-cell pack. 上部分初始 C1 represents the initial state of charge of the first sub-battery pack, C2 represents the second change in charge of the second sub-battery pack, and C0 represents the total capacity of the power battery.

[0037] Optionally, the step of controlling a second charge transfer between the first sub-battery pack and the second sub-battery pack based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal, includes:

[0038] Control the second power transfer between the first sub-battery pack and the second sub-battery pack to obtain the third power change value of the first sub-battery pack and the fourth power change value of the second sub-battery pack;

[0039] The third state of charge of the first sub-battery pack is obtained based on the first state of charge, the third change in charge value, and the total capacity of the power battery.

[0040] The fourth state of charge of the second sub-battery pack is obtained based on the second state of charge, the fourth change in charge value, and the total capacity of the power battery.

[0041] When the third state of charge and the fourth state of charge are equal, the second charge transfer between the first sub-battery pack and the second sub-battery pack is stopped.

[0042] Optionally, the step of controlling the second power transfer between the first and second sub-battery packs to obtain a third power change value for the first sub-battery pack and a fourth power change value for the second sub-battery pack includes:

[0043] Control the second power transfer between the first sub-battery pack and the second sub-battery pack, and determine the third current of the first sub-battery pack during the second power transfer, the fourth current of the second sub-battery pack during the second power transfer, and the second duration of the second power transfer.

[0044] The product of the third current and the second duration is determined as the third change value of the charge of the first sub-battery pack, and the product of the fourth current and the second duration is determined as the fourth change value of the charge of the second sub-battery pack.

[0045] Optionally, when the first sub-battery pack is charging, the method for calculating the third state of charge is as follows:

[0046] SOC 上部分 =SOC 上部分 +C1' / C0

[0047] When the first sub-battery pack is charging, the method for calculating the fourth state of charge is as follows:

[0048] SOC 下部分 =SOC 下部分 -C2' / C0

[0049] Among them, SOC 上部分 'This is the third state of charge, SOC' 下部分 'This is the fourth state of charge, SOC' 上部分 The first state of charge (SOC) of the first sub-cell pack. 下部分 C1' is the second state of charge of the second sub-battery pack, C2' is the third change in charge, C0 is the fourth change in charge, and C0 is the total capacity of the power battery.

[0050] Optionally, when the first sub-battery pack is discharging, the method for calculating the third state of charge is as follows:

[0051] SOC 上部分 =SOC 上部分 -C1' / C0

[0052] When the first sub-battery pack is discharging, the method for calculating the fourth state of charge is as follows:

[0053] SOC 下部分 =SOC 下部分 +C2' / C0

[0054] Among them, SOC 上部分 'This is the third state of charge, SOC' 下部分 'This is the fourth state of charge, SOC' 上部分 The first state of charge (SOC) of the first sub-cell pack. 下部分C1' is the second state of charge of the second sub-battery pack, C2' is the third change in charge, C0 is the fourth change in charge, and C0 is the total capacity of the power battery.

[0055] Optionally, before controlling the first power transfer between the first sub-battery pack and the second sub-battery pack to bring the voltage of a single cell in the first sub-battery pack into the target voltage range, the method further includes:

[0056] Obtain the temperature of the power battery;

[0057] Based on the temperature of the power battery, determine the pre-calibrated open-circuit voltage state-of-charge curve, charging voltage state-of-charge curve, and discharging voltage state-of-charge curve corresponding to that temperature.

[0058] The target voltage range is determined from the charging voltage state-of-charge curve or the discharging voltage state-of-charge curve based on the voltage of a single cell in the power battery and the open-circuit voltage state-of-charge curve.

[0059] Optionally, the open-circuit voltage state-of-charge curve includes a first voltage rise interval, a second voltage rise interval, and a third voltage rise interval, as well as a first voltage plateau interval and a second voltage plateau interval; the first voltage plateau interval is located between the first voltage rise interval and the second voltage rise interval, the second voltage plateau interval is located between the second voltage rise interval and the third voltage rise interval, and the minimum voltage of the third voltage rise interval is greater than the maximum voltage of the first voltage rise interval;

[0060] The step of determining the target voltage range from the charging voltage state-of-charge curve or the discharging voltage state-of-charge curve based on the voltage of a single cell in the power battery and the open-circuit voltage state-of-charge curve includes:

[0061] When the voltage of a single cell in the power battery is in the first voltage plateau period range, the state of charge range corresponding to the first voltage rise range on the open circuit voltage state of charge curve is determined, and the target voltage range is determined according to the voltage range corresponding to the discharge voltage state of charge curve based on the state of charge range.

[0062] When the voltage of a single cell in the power battery is in the second voltage plateau period range, the third voltage rise range is determined to be the state of charge range corresponding to the open circuit voltage state of charge curve, and the target voltage range is determined according to the voltage range corresponding to the charging voltage state of charge curve.

[0063] Optionally, after obtaining the voltage of a single cell in the power battery, the method further includes:

[0064] When the voltage of a single cell in the power battery is in a non-target plateau range, the state of charge of the power battery is determined according to the correspondence between the voltage of the single cell and the state of charge of the power battery.

[0065] According to a second aspect of the present disclosure, a battery control system is provided, comprising:

[0066] A power battery, comprising a first sub-battery pack and a second sub-battery pack connected in series.

[0067] A motor controller, which is connected to the first sub-battery pack and the second sub-battery pack respectively;

[0068] A current acquisition component, which is connected to the first sub-battery pack and the second sub-battery pack respectively;

[0069] A battery management controller, connected to the motor controller and the current acquisition component, is configured to perform the state of charge determination method described in the first aspect of this disclosure.

[0070] Optionally, the first sub-battery pack is connected to the positive terminal of the motor controller via the positive terminal interface of the power battery and a first connecting line;

[0071] The second sub-battery pack is connected to the negative terminal of the motor controller via the negative terminal interface of the power battery and a second connecting line;

[0072] The first sub-battery pack and the second sub-battery pack are connected to motor point N via a third connecting line;

[0073] The current acquisition component includes at least two current sampling sensors, which are disposed on any two of the first connecting line, the second connecting line, and the third connecting line. According to a third aspect of this disclosure, a non-transitory computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the state of charge determination method described in the first aspect of this disclosure.

[0074] According to a fourth aspect of the present disclosure, a power battery state of charge determination device is provided, comprising:

[0075] A memory on which computer programs are stored;

[0076] A processor is configured to execute the computer program in the memory to implement the steps of the method for determining the state of charge as described in the first aspect of this disclosure.

[0077] According to a fifth aspect of the present disclosure, a vehicle is provided, including a battery control system as described in the second aspect of the present disclosure, wherein a battery management controller in the battery control system is configured to perform the steps of the state of charge determination method as described in the first aspect of the present disclosure.

[0078] Through the above technical solution, after controlling the first power transfer between the first sub-battery pack and the second sub-battery pack, the first power transfer between the first sub-battery pack and the second sub-battery pack is controlled to be carried out for a second power transfer, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal, and the state of charge when the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal is determined as the state of charge of the power battery. During the first and second power transfer processes of the first and second battery packs, the state of charge (SOC) of both battery packs can be calculated relatively accurately. Due to the consistency of individual cells in the power battery—that is, the charge of each cell is equal—when the SOC of the first and second sub-battery packs are equal, the SOC at which the first and second sub-battery packs are equal can be determined as the SOC of the power battery. This allows for a relatively accurate SOC of the power battery, and the accurate SOC can be obtained at any stage of the power battery's SOC without the need to establish a battery model, reducing workload and saving time and resources.

[0079] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0080] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0081] Figure 1 This is a flowchart illustrating a method for determining the state of charge according to an exemplary embodiment.

[0082] Figure 2 This is a flowchart illustrating a method for determining a first state of charge and a second state of charge according to an exemplary embodiment.

[0083] Figure 3 This is a schematic diagram illustrating the relationship between state of charge and voltage according to an exemplary embodiment.

[0084] Figure 4 This is a flowchart illustrating another method for determining the state of charge according to an exemplary embodiment.

[0085] Figure 5This is a flowchart illustrating yet another method for determining the state of charge, according to an exemplary embodiment.

[0086] Figure 6 This is a schematic diagram of the structure of a battery control system according to an exemplary embodiment.

[0087] Figure 7 This is a block diagram illustrating a state of charge determination device according to an exemplary embodiment.

[0088] Explanation of reference numerals in the attached figures

[0089] 1. First sub-battery pack; 2. Second sub-battery pack; 3. Motor controller; 4. First connecting wire; 5. Second connecting wire; 6. Third connecting wire. Detailed Implementation

[0090] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0091] In related technologies, the open-circuit voltage method can be used to determine the state of charge of a battery. However, this method is very ineffective for lithium iron phosphate batteries. The open-circuit voltage state of charge curve of lithium iron phosphate batteries has a long plateau period. The accurate state of charge of the battery cannot be determined during the plateau period. Only when the state of charge of the battery is below 20% or above 95% can the open-circuit voltage method estimate the state of charge of the battery.

[0092] The method for determining the state of charge of a battery using Kalman filtering requires the establishment of a reliable battery model, which involves a large amount of matching work and consumes a lot of time and resources.

[0093] To address the aforementioned problems, this disclosure provides a method, apparatus, medium, battery control system, and vehicle for determining the state of charge (SOC). By dividing the power battery into a first sub-battery pack and a second sub-battery pack, and actively controlling a first charge transfer between the first and second sub-battery packs, followed by a second charge transfer, the SOC of the first and second sub-battery packs is made equal, thus obtaining the SOC of the power battery. This method provides a relatively accurate SOC of the power battery, applicable to any stage of the battery's charge, without requiring a battery model, reducing workload and saving time and resources.

[0094] Figure 1 This is a flowchart illustrating a method for determining the state of charge according to an exemplary embodiment, such as... Figure 1As shown, this method can be applied to a power battery, which includes a first sub-battery pack and a second sub-battery pack. The method for determining the state of charge includes the following steps:

[0095] In step S101, after controlling the first power transfer between the first sub-battery pack and the second sub-battery pack, the first power transfer between the first sub-battery pack and the second sub-battery pack is controlled to be performed a second time, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal.

[0096] In this embodiment, the battery management controller can respond to the state of charge estimation command and execute the method for determining the state of charge of the power battery. The state of charge estimation command can be generated manually or actively, including but not limited to through diagnostic equipment, in-vehicle buttons, or multimedia screen control. Alternatively, the battery control system can automatically trigger the generation of the state of charge estimation command when it recognizes that the vehicle has been in a static or locked anti-theft state for a long time.

[0097] Upon receiving the state of charge estimation command, the system can control a first power transfer between the first sub-battery pack and the second sub-battery pack, and then control a second power transfer between the first sub-battery pack and the second sub-battery pack, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal.

[0098] In one feasible implementation, with the goal of equalizing the state of charge (SOC) of the first sub-battery pack and the second sub-battery pack, when the first SOC of the first sub-battery pack is greater than the second SOC of the second sub-battery pack, the first sub-battery pack is controlled to charge the second sub-battery pack; when the first SOC of the first sub-battery pack is less than the second SOC of the second sub-battery pack, the second sub-battery pack is controlled to charge the first sub-battery pack. The SOC of the first and second sub-battery packs is calculated in real time, and when the SOC of the first and second sub-battery packs are equal, the second charge transfer between the first and second sub-battery packs is stopped.

[0099] In step S102, the state of charge of the power battery is determined when the state of charge of the first sub-battery pack is equal to that of the second sub-battery pack.

[0100] In this embodiment, during the first and second power transfer processes of the first and second battery packs, the state of charge (SOC) of the first and second battery packs can be calculated relatively accurately. Due to the consistency of individual cells in the power battery, i.e., the amount of charge in each cell is equal, when the SOC of the first and second sub-battery packs are equal, the SOC of the power battery can be determined as the SOC of the power battery. This allows for a relatively accurate SOC of the power battery, and the accurate SOC of the power battery can be obtained at any stage of the power battery's SOC. Furthermore, it eliminates the need to establish a battery model, reducing workload and saving time and resources.

[0101] In one possible implementation, a first power transfer is controlled between the first sub-battery pack and the second sub-battery pack to obtain a first state of charge (SOC) of the first sub-battery pack and a second SOC of the second sub-battery pack. After obtaining the SOC of the first sub-battery pack and the second SOC of the second sub-battery pack, a second power transfer is controlled between the first sub-battery pack and the second sub-battery pack based on the SOC of the first sub-battery pack and the second SOC of the second sub-battery pack, so that the SOC of the first sub-battery pack and the SOC of the second sub-battery pack are equal.

[0102] The battery management controller is calibrated with multiple open-circuit voltage state-of-charge curves under different temperatures and constant DC current I. The current temperature of the power battery can be obtained, and the corresponding open-circuit voltage state-of-charge curve can be determined based on the current temperature of the power battery.

[0103] In one possible implementation, before controlling the first power transfer between the first sub-battery pack and the second sub-battery pack, the voltage of a single cell in the power battery can be obtained first. When the voltage of a single cell in the power battery is within the target plateau range, the first power transfer between the first sub-battery pack and the second sub-battery pack is controlled.

[0104] In this embodiment, the voltage of a single cell in the power battery is acquired, and it is determined whether this voltage is within the target plateau period range. Within the target plateau period range, the voltage does not change with the state of charge (SOC) of the power battery, or the voltage changes very little with the SOC, making it impossible to directly determine the SOC of the power battery based on the voltage of a single cell. However, outside the target plateau period range, the voltage of a single cell corresponds to the SOC of the power battery; that is, the voltage changes significantly with the SOC, and the SOC of the power battery can be directly determined based on the voltage of a single cell. The target plateau period range can be determined based on the open-circuit voltage SOC curve. For example, the plateau period range in the open-circuit voltage SOC curve at the current temperature can be directly determined as the target plateau period range. To reduce error, a preset fluctuation range can be expanded from the plateau period range in the open-circuit voltage SOC curve at the current temperature to serve as the target plateau period range.

[0105] In one possible implementation, controlling a first power transfer between the first sub-battery pack and the second sub-battery pack, and obtaining a first state of charge of the first sub-battery pack and a second state of charge of the second sub-battery pack, may include the following steps:

[0106] In step S201, a first power transfer is controlled between the first sub-battery pack and the second sub-battery pack to bring the voltage of a single cell in the first sub-battery pack into the target voltage range.

[0107] In step S202, when the voltage of a single cell in the first sub-battery pack reaches the target voltage range, the target voltage of the single cell in the first sub-battery pack, the first charge change value of the first sub-battery pack, and the second charge change value of the second sub-battery pack are obtained.

[0108] In step S203, the first state of charge of the first sub-battery pack is obtained based on the target voltage.

[0109] In step S204, the second state of charge of the second sub-battery pack is obtained based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery.

[0110] In this embodiment, when the voltage of a single cell in the power battery is within the target plateau range, a target voltage range can be determined first. Within this target voltage range, the voltage of a single cell in the power battery corresponds to the state of charge of the power battery. Then, with the goal of the voltage of a single cell in the first sub-battery pack reaching the target voltage range, the first sub-battery pack and the second sub-battery pack are controlled to perform a first charge transfer. Before the charge transfer, the first sub-battery pack and the second sub-battery pack have the same state of charge. The state of the first sub-battery pack during the charge transfer can be determined based on the relationship between the voltage of a single cell in the first sub-battery pack and the target voltage range. This state is either charging or discharging. When the voltage of a single cell in the first sub-battery pack is greater than the maximum voltage in the target voltage range, the first sub-battery pack is determined to discharge during the charge transfer. When the voltage of a single cell in the first sub-battery pack is less than the minimum voltage in the target voltage range, the first sub-battery pack is determined to charge during the charge transfer.

[0111] When the voltage of a single cell in the first sub-battery pack reaches the target voltage range, the power transfer between the first and second sub-battery packs is stopped. The target voltage of a single cell in the first sub-battery pack can then be obtained. This target voltage is the voltage at which the voltage of a single cell in the first sub-battery pack no longer changes after the power transfer between the first and second sub-battery packs is completed. For example, the resting time can be determined based on the temperature of a single cell in the first sub-battery pack at the end of the power transfer. After the resting time, the voltage of a single cell in the first sub-battery pack can be obtained as the target voltage of a single cell in the first sub-battery pack.

[0112] In one possible implementation, obtaining the first charge change value of the first sub-battery pack and the second charge change value of the second sub-battery pack may include the following methods:

[0113] The first current of the first sub-battery pack during the first power transfer, the second current of the second sub-battery pack during the first power transfer, and the first duration of the first power transfer are obtained.

[0114] The product of the first current and the first duration is determined as the first change in charge of the first sub-battery pack, and the product of the second current and the first duration is determined as the second change in charge of the second sub-battery pack.

[0115] In this embodiment, when power transfer occurs between the first sub-battery pack and the second sub-battery pack, a current sampling sensor collects the current on any two of the first, second, and third connecting lines and sends it to the battery management controller. The battery management controller can obtain the first current of the first sub-battery pack during the first power transfer and the second current of the second sub-battery pack during the first power transfer based on the current collected by the current sampling sensor on any two of the first, second, and third connecting lines. It can also calculate the first duration of the first power transfer. Then, the product of the first current and the first duration can be determined as the first power change value of the first sub-battery pack, and the product of the second current and the first duration can be determined as the second power change value of the second sub-battery pack.

[0116] Since the target voltage is within the target voltage range, and within this range, the state of charge (SOC) of the power battery corresponds to the voltage of a single cell, the first SOC of the first sub-battery pack can be obtained based on the target voltage and the correspondence between the voltage of a single cell and the SOC of the power battery. Specifically, the corresponding charging voltage SOC curve and discharging voltage SOC curve can be determined based on the temperature of each cell in the first sub-battery pack. If the first sub-battery pack is charging, the corresponding first SOC is obtained based on the charging voltage SOC curve using the target voltage; if the first sub-battery pack is discharging, the corresponding first SOC is obtained based on the discharging voltage SOC curve using the target voltage.

[0117] The second state of charge of the second sub-battery pack can be obtained based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery. The first state of charge of the first sub-battery pack is the state of charge of the first sub-battery pack after the first charge transfer, and the second state of charge of the second sub-battery pack is the state of charge of the second sub-battery pack after the first charge transfer.

[0118] In one possible implementation, controlling a second charge transfer between the first and second sub-battery packs to make the state of charge (SOC) of the first and second sub-battery packs equal may include:

[0119] Based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, a second power transfer is controlled between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal.

[0120] In this embodiment, based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, the second power transfer between the first and second sub-battery packs can be controlled relatively accurately. In one feasible embodiment, obtaining the second state of charge of the second sub-battery pack based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery may include:

[0121] The initial state of charge of the first sub-battery pack is obtained based on the first state of charge, the first change in charge value, and the total capacity of the power battery.

[0122] The second state of charge is obtained based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery.

[0123] In this embodiment, the corresponding charging voltage state of charge curve and discharging voltage state of charge curve can be determined based on the temperature of a single cell in the first sub-battery pack. If the first sub-battery pack is charging, the corresponding first state of charge is obtained based on the target voltage and the charging voltage state of charge curve; if the first sub-battery pack is discharging, the corresponding first state of charge is obtained based on the target voltage and the discharging voltage state of charge curve.

[0124] The initial state of charge of the first sub-battery pack can be obtained based on the first state of charge, the first change in charge value, and the total capacity of the power battery. The calculation method for the initial state of charge of the first sub-battery pack is as follows:

[0125] When the first sub-cell pack discharges, the SOC 上部分初始 =SOC 下部分初始 =SOC 上部分 +C1 / C0

[0126] When the first sub-battery pack is charging, the SOC 上部分初始 =SOC 下部分初始 =SOC 上部分 -C1 / C0

[0127] Among them, SOC 上部分初始 The initial state of charge (SOC) of the first sub-cell pack. 下部分初始 The initial state of charge (SOC) of the second sub-cell pack. 上部分 C1 represents the first state of charge of the first sub-battery pack, C0 represents the first change in charge of the first sub-battery pack, and C0 represents the total capacity of the power battery.

[0128] Then, based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery, the second state of charge is obtained. The calculation method for the second state of charge can be as follows:

[0129] When the second sub-battery pack is charging, the SOC下部分 =SOC 上部分初始 +C2 / C0

[0130] When the second sub-cell pack discharges, the State of Charge (SOC) 下部分 =SOC 上部分初始 -C2 / C0

[0131] Among them, SOC 下部分 The second state of charge (SOC) of the second sub-cell pack. 上部分初始 C1 represents the initial state of charge of the first sub-battery pack, C2 represents the second change in charge of the second sub-battery pack, and C0 represents the total capacity of the power battery.

[0132] In one feasible implementation, based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, a second charge transfer is controlled between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal. This may include:

[0133] A second power transfer is controlled between the first sub-battery pack and the second sub-battery pack to obtain a third power change value for the first sub-battery pack and a fourth power change value for the second sub-battery pack.

[0134] The third state of charge of the first sub-battery pack is obtained based on the first state of charge, the third change in charge value, and the total capacity of the power battery.

[0135] The fourth state of charge (SOC) of the second sub-battery pack is obtained based on the second SOC, the fourth change in charge value, and the total capacity of the power battery. When the third SOC and the fourth SOC are equal, the second charge transfer between the first and second sub-battery packs is stopped.

[0136] In this embodiment, a second power transfer can be controlled between the first and second sub-battery packs to make their states of charge equal. During the second power transfer, the third and fourth power change values ​​of the first and second sub-battery packs are acquired in real time. Based on the first state of charge, the third power change value, and the total capacity of the power battery, the third and fourth states of charge of the first and second sub-battery packs can be obtained. The third state of charge of the first sub-battery pack is the real-time state of charge of the first sub-battery pack during the second power transfer, and the fourth state of charge of the second sub-battery pack is the real-time state of charge of the second sub-battery pack during the second power transfer.

[0137] Specifically, controlling a second power transfer between the first and second sub-battery packs to obtain a third power change value for the first sub-battery pack and a fourth power change value for the second sub-battery pack includes:

[0138] Control the second power transfer between the first sub-battery pack and the second sub-battery pack, and determine the third current of the first sub-battery pack during the second power transfer, the fourth current of the second sub-battery pack during the second power transfer, and the second duration of the second power transfer.

[0139] The product of the third current and the second duration is determined as the third change in charge of the first sub-battery pack, and the product of the fourth current and the second duration is determined as the fourth change in charge of the second sub-battery pack.

[0140] When the first sub-battery pack is charging, the calculation methods for the third and fourth states of charge can be as follows:

[0141] SOC 上部分 =SOC 上部分 +C1' / C0

[0142] SOC 下部分 =SOC 下部分 -C2' / C0

[0143] Among them, SOC 上部分 'This is the third state of charge, SOC' 下部分 'This is the fourth state of charge, SOC' 上部分 The first state of charge (SOC) of the first sub-cell pack. 下部分 C1' represents the second state of charge of the second sub-battery pack, C2' represents the third change in charge, and C2' represents the fourth change in charge.

[0144] When the first sub-cell pack is discharging, the calculation methods for the third and fourth states of charge can be as follows:

[0145] SOC 上部分 =SOC 上部分 -C1' / C0

[0146] SOC 下部分 =SOC 下部分 +C2' / C0

[0147] The real-time state of charge of the first sub-battery pack and the real-time state of charge of the second sub-battery pack can be obtained using the above calculation method.

[0148] When the third state of charge and the fourth state of charge are equal, that is, when the real-time state of charge of the first sub-battery pack and the real-time state of charge of the second sub-battery pack are equal, the transfer of power between the first sub-battery pack and the second sub-battery pack is stopped, and the corresponding third state of charge and fourth state of charge are obtained. At this time, the third state of charge or the fourth state of charge can be determined as the state of charge of the power battery.

[0149] In one feasible implementation, before controlling a first power transfer between the first sub-battery pack and the second sub-battery pack to bring the voltage of a single cell in the first sub-battery pack into a target voltage range, the method further includes:

[0150] Obtain the temperature of the power battery.

[0151] Based on the temperature of the power battery, determine the pre-calibrated open-circuit voltage state-of-charge curve, charging voltage state-of-charge curve, and discharging voltage state-of-charge curve corresponding to that temperature.

[0152] Based on the voltage and open-circuit voltage state-of-charge curves of a single cell in the power battery, the target voltage range is determined from the charging voltage state-of-charge curve or the discharging voltage state-of-charge curve.

[0153] In this embodiment, the battery management controller is calibrated with multiple open-circuit voltage state-of-charge (POC) curves, charging voltage POC curves, and discharging voltage POC curves under different temperatures and a constant DC current I. The temperature of the power battery and the voltage of each individual cell within the power battery can be acquired. The temperature of the power battery can be considered the temperature of each individual cell. Based on this temperature, the corresponding pre-calibrated open-circuit voltage POC curve, charging voltage POC curve, and discharging voltage POC curve are determined. Furthermore, based on the voltage of each individual cell and the open-circuit voltage POC curve, a target voltage range is determined from either the charging voltage POC curve or the discharging voltage POC curve.

[0154] Figure 3 This is a schematic diagram illustrating the relationship between state of charge and voltage according to an exemplary embodiment, such as... Figure 3 As shown, SOC-U 放 The discharge voltage-state-of-charge curve, SOC-U 充The charging voltage state-of-charge curve (SOC-OCV) is the open-circuit voltage state-of-charge curve. In one feasible implementation, the open-circuit voltage state-of-charge curve may include a first voltage rise interval, a second voltage rise interval, and a third voltage rise interval, as well as a first voltage plateau interval and a second voltage plateau interval. The first voltage plateau interval lies between the first and second voltage rise intervals, the second voltage plateau interval lies between the second and third voltage rise intervals, and the minimum voltage of the third voltage rise interval is greater than the maximum voltage of the first voltage rise interval. A target plateau interval and a non-target plateau interval can be determined based on the first, second, and third voltage rise intervals, as well as the first and second voltage plateau intervals.

[0155] Based on the voltage and open-circuit voltage state-of-charge (POC) curves of individual cells in a power battery, a target voltage range can be determined from the charging voltage POC curve or the discharging voltage POC curve. This may include:

[0156] When the voltage of a single cell in the power battery is in the first voltage plateau period range, the state of charge range corresponding to the first voltage rise range on the open circuit voltage state of charge curve is determined, and the target voltage range is determined based on the voltage range corresponding to the discharge voltage state of charge curve of the state of charge range.

[0157] When the voltage of a single cell in the power battery is in the second voltage plateau period range, the state of charge range corresponding to the third voltage rise range on the open-circuit voltage state of charge curve is determined, and the target voltage range is determined based on the voltage range corresponding to the charging voltage state of charge curve of this state of charge range.

[0158] In this embodiment, for the same type of battery, the trends of its open-circuit voltage state-of-charge curve, charging voltage state-of-charge curve, and discharging voltage state-of-charge curve are the same. However, for the same state-of-charge range, the voltages corresponding to the open-circuit voltage state-of-charge curve, charging voltage state-of-charge curve, and discharging voltage state-of-charge curve are somewhat different.

[0159] Therefore, when the voltage of a single cell in the power battery is within the first voltage plateau period, the state of charge (SOC) range corresponding to the first voltage rise interval on the open-circuit voltage SOC curve is determined, and the target voltage range is determined based on the voltage range corresponding to this SOC range on the discharge voltage SOC curve. Since the first voltage rise interval is adjacent to the first voltage plateau period, and the relationship between voltage and SOC in the first voltage rise interval is more pronounced than in the second voltage rise interval, and the SOC range in the second voltage rise interval is smaller, making it easier for charge transfer to exceed the second voltage rise interval, the voltage range corresponding to the first voltage rise interval on the discharge voltage SOC curve is selected as the target voltage range.

[0160] When the voltage of a single cell in the power battery is within the second voltage plateau period, the state of charge (SOC) range corresponding to the third voltage rise interval on the open-circuit voltage SOC curve is determined. The target voltage range is then determined based on the voltage range corresponding to this SOC range on the charging voltage SOC curve. Since the third voltage rise interval is adjacent to the second voltage plateau period, and the relationship between voltage and SOC in the third voltage rise interval is more pronounced than in the second voltage rise interval, and the SOC range in the second voltage rise interval is smaller, making it easier for charge transfer to exceed the second voltage rise interval, the voltage range corresponding to the third voltage rise interval on the charging voltage SOC curve is selected as the target voltage range.

[0161] Figure 4 This is a flowchart illustrating another method for determining the state of charge according to an exemplary embodiment, such as... Figure 3 and Figure 4 As shown, it includes the following steps:

[0162] In step S401, the motor control topology is reused to control the upper battery pack to discharge according to a constant DC current I to charge the lower battery pack, and then step S402 is executed.

[0163] In step S402, it is determined whether there is a single cell voltage U in the upper part of the battery pack. 上部分 >U 2放 If -A' is true, proceed to step S403; otherwise, return to step S401.

[0164] In step S403, the cumulative charging capacity of the upper battery pack is C1 and the cumulative charging capacity of the lower battery pack is C2, and then step S404 is executed.

[0165] In step S404, the system is left to stand for a certain time t, based on SOC-U 放 The curve estimates the current SOC of the upper part of the battery pack. 上部分 Based on the capacity C1, the SOC of the upper battery pack before charging is calculated to be...

[0166] SOC 上部分初始 =SOC 下部分初始 Then, proceed to step S405.

[0167] In step S405, based on the discharge capacity C2 and SOC 下部分初始 The current SOC of the lower battery pack is calculated. 下部分 Then proceed to step S406.

[0168] In step S406, the motor control topology is reused to control the lower battery pack to discharge according to a constant DC current I to charge the upper battery pack, and then step S407 is executed.

[0169] In step S407, the charging capacity C1' of the upper battery pack and the discharging capacity C2' of the lower battery pack are accumulated, and the SOC of the upper battery pack is calculated in real time. 上部分 'and the lower part of the battery pack SOC is SOC 下部分 ', and execute step S408.

[0170] In step S408, it is determined whether a SOC exists. 上部分 =SOC 下部分 '.

[0171] If so, then SOC 上部分 'or SOC 下部分 'Identify the state of charge of the power battery;'

[0172] If not, return to step S407.

[0173] Figure 5 This is a flowchart illustrating yet another method for determining the state of charge according to an exemplary embodiment, such as... Figure 3 and Figure 5 As shown, it includes the following steps:

[0174] In step S501, the motor control topology is reused to control the lower battery pack to discharge according to a constant DC current I, charge the upper battery pack, and then step S502 is executed.

[0175] In step S502, it is determined whether there is a single cell voltage U in the upper part of the battery pack. 上部分 >U 3充 If +B' is true, proceed to step S503; otherwise, return to step S501.

[0176] In step S503, the cumulative charging capacity of the upper battery pack is C3 and the cumulative charging capacity of the lower battery pack is C4, and then step S504 is executed.

[0177] In step S504, the system is left to stand for a certain time t, based on SOC-U 充 The curve estimates the current SOC of the upper part of the battery pack. 上部分 Based on the capacity C3, the calculated SOC of the upper battery pack before charging is:

[0178] SOC 上部分初始 =SOC 下部分初始 Then, proceed to step S505.

[0179] In step S505, based on the discharge capacity C4 and SOC 下部分初始 The current SOC of the lower battery pack is calculated. 下部分 Then proceed to step S506.

[0180] In step S506, the motor control topology is reused to control the upper battery pack to discharge according to a constant DC current I to charge the lower battery pack, and then step S507 is executed.

[0181] In step S407, the charging capacity C3' of the upper battery pack and the discharging capacity C4' of the lower battery pack are accumulated, and the SOC of the upper battery pack is calculated in real time. 上部分 'and the lower part of the battery pack SOC is SOC 下部分 ', and execute step S508.

[0182] In step S508, it is determined whether a SOC exists. 上部分 =SOC 下部分 '.

[0183] If so, then SOC 上部分 'or SOC 下部分 'Identify the state of charge of the power battery;'

[0184] If not, return to step S507.

[0185] In the example above, we can first determine the voltage range of a single cell voltage U. If U < U2-A, then we can estimate the SOC of the battery according to the SOC-OCV curve of the current temperature range, where A is the voltage fluctuation range of the battery during the voltage plateau period. For lithium iron phosphate batteries, the value of A is about 5-10mV.

[0186] If the voltage U of a single battery cell is within the voltage range: U2-A≤U≤U2+A, the upper battery pack is controlled to discharge at a constant DC current I to charge the lower battery pack by using a reused motor control topology. During this process, the battery management controller collects the voltage U of a single cell in the upper battery pack in real time. 上部分 The upper battery pack's cumulative charging capacity C1, and the lower battery pack's single-cell voltage U. 下部分The cumulative charging capacity of the lower battery pack, C2, is calculated until the lowest single-cell voltage, U, of the upper battery pack is reached. 上部分 <U 2放 -A' (where A' is the voltage fluctuation range during the battery's voltage plateau period; for lithium iron phosphate batteries, the value of A' is approximately 5-10mV), the motor control stops the upper battery pack from charging the lower battery pack. After a certain period of time t (the value of t is based on the time required from the end of battery charging / discharging to the point where the battery voltage no longer changes at different temperatures), the SOC-U is calculated based on this temperature range. 放 The curve estimates the current SOC of the upper part of the battery pack. 上部分 Based on the charging capacity C1, the SOC of the upper battery pack before charging (and equal to the SOC of the lower battery pack before discharging) is calculated as the SOC. 上部分初始 =SOC 下部分初始 =SOC 上部分 +C1 / C0, where C0 is the battery pack capacity. Based on the discharge capacity C2 and SOC. 下部分初始 The current SOC of the lower battery pack is calculated. 下部分 =SOC 下部分初始 +C2 / C0.

[0187] The motor control topology is reused to control the lower battery pack to discharge at a constant DC current I, charging the upper battery pack. The charging capacity C1' of the upper battery pack and the discharging capacity C2' of the lower battery pack are accumulated in real time, and the results are based on the accumulated capacity and the State of Charge (SOC). 上部分 SOC 下部分 The SOC of the upper battery pack is calculated as follows: 上部分 'and the lower part of the battery pack SOC is SOC 下部分 ', until SOC 上部分 =SOC 下部分 The control motor stops charging the upper battery pack from the lower battery pack. At this point, the SOC of the battery pack is estimated, and the current SOC of the battery pack is the final SOC. 上部分 '(or SOC) 下部分 ').

[0188] If the voltage U of a single cell is in the voltage range: U2+A<U<U3-B, estimate the SOC of the battery according to the SOC-OCV curve of the current temperature range, where B is the voltage fluctuation range of the battery during the voltage plateau period. For lithium iron phosphate batteries, the value of B is about 5-10mV.

[0189] If the voltage U of a single battery cell is within the voltage range: U3-B≤U≤U3+B, the lower battery pack is controlled to discharge at a constant DC current I to charge the upper battery pack by using a reused motor control topology. During this process, the battery management controller collects the voltage U of a single cell in the upper battery pack in real time.上部分 The upper battery pack's cumulative charging capacity C3, and the lower battery pack's single-cell voltage U. 下部分 The cumulative charging capacity of the lower battery pack is C4, up to the lowest single-cell voltage U of the upper battery pack. 上部分 >U 3充 +B' (where B' is the voltage fluctuation range during the battery's voltage plateau period; for lithium iron phosphate batteries, the value of B' is approximately 5-10mV), the motor control stops the lower battery pack from charging the upper battery pack. After a certain period of time t (the value of t is based on the time required from the end of battery charging / discharging to the point where the battery voltage no longer changes at different temperatures), the SOC-U is calculated based on this temperature range. 充 The curve estimates the current SOC of the upper part of the battery pack. 上部分 Based on the charging capacity C3, the SOC of the upper battery pack before charging (and equal to the SOC of the lower battery pack before discharging) is calculated as SOC. 上部分初始 =SOC 下部分初始 =SOC 上部分 -C3 / C0, where C0 is the battery pack capacity. Based on discharge capacity C4 and SOC. 下部分初始 The current SOC of the lower battery pack is calculated. 下部分 =SOC 下部分初始 -C4 / C0. The motor control topology is reused to control the upper battery pack to discharge at a constant DC current I, charging the lower battery pack. The discharge capacity C3' of the upper battery pack and the charging capacity C4' of the lower battery pack are accumulated in real time, and the accumulated capacity is calculated based on the SOC. 上部分 SOC 下部分 Real-time calculation of the upper battery pack's SOC (State of Charge) 上部分 'and the lower part of the battery pack SOC is SOC 下部分 ', until SOC 上部分 =SOC 下部分 The motor control system stops the upper battery pack from charging the lower battery pack. At this point, the SOC of the battery pack is estimated, and the current SOC of the battery pack is the final SOC. 上部分 '(or SOC) 下部分 ').

[0190] If the voltage of a single battery cell U > U3 + B, estimate the battery's SOC based on the SOC-OCV curve for the current temperature range.

[0191] Among them, the charging and discharging current control of the battery includes, but is not limited to, constant current DC current, a combination of AC currents such as sine wave, square wave or trapezoidal wave, irregular waveform current and bias control current of the above waveforms.

[0192] Figure 6This is a structural intent of a battery control system according to an exemplary embodiment, such as Figure 6 As shown, the battery control system includes:

[0193] The power battery includes a first sub-battery pack 1 and a second sub-battery pack 2 connected in series.

[0194] Motor controller 3, which is connected to the first sub-battery pack 1 and the second sub-battery pack 2 respectively;

[0195] A current acquisition component is connected to the first sub-battery pack and the second sub-battery pack respectively;

[0196] A battery management controller, which is connected to the motor controller 3 and the current acquisition component, is configured to perform the state of charge determination method in the above embodiments.

[0197] In this embodiment, the battery control system includes a power battery, a motor controller 3, a current acquisition component, and a battery management controller. The power battery includes a first sub-battery pack 1 and a second sub-battery pack 2 connected in series. The number of individual cells in the first sub-battery pack 1 and the second sub-battery pack 2 may be equal or unequal. For example, the number of individual cells in the first sub-battery pack 1 and the second sub-battery pack 2 may deviate within a preset range, but this deviation must not exceed the preset range. This is to prevent insufficient charge in either the first sub-battery pack 1 or the second sub-battery pack 2, which would prevent enough charge from being transferred to bring the voltage of the individual cells in the first sub-battery pack 1 to the target voltage range.

[0198] The motor controller 3 is connected to the first sub-battery pack 1 and the second sub-battery pack 2 respectively. The motor controller 3 can receive and respond to the instructions of the battery management controller and control the power transfer between the first sub-battery pack 1 and the second sub-battery pack 2.

[0199] The current acquisition component is connected to the power battery and can acquire the current of the first sub-battery pack 1 and the second sub-battery pack 2 during the power transfer between the first sub-battery pack 1 and the second sub-battery pack 2. The acquired current is sent to the battery management controller so that the battery management controller can determine the change in power of the first sub-battery pack 1 and the second sub-battery pack 2 during the power transfer based on the acquired current and the power transfer duration.

[0200] The battery management controller is connected to the motor controller 3 and the current acquisition component. It can control the transfer of power between the first sub-battery pack 1 and the second sub-battery pack 2 by sending control commands to the motor controller 3, and determine the state of charge of the power battery based on the change in power value of the first sub-battery pack 1 and the second sub-battery pack 2 during the power transfer.

[0201] In one feasible implementation, the first sub-battery pack 1 is connected to the positive terminal of the motor controller 3 via the positive terminal interface of the power battery and the first connecting line 4;

[0202] The second sub-battery pack 2 is connected to the negative terminal of the motor controller 3 via the negative terminal interface of the power battery and the second connecting line 5.

[0203] The first sub-battery pack 1 and the second sub-battery pack 2 are connected to motor point N via a third connecting line 6;

[0204] The current acquisition component includes at least two current sampling sensors, with a current sampling sensor installed on any two of the first connecting line 4, the second connecting line 5, and the third connecting line 6.

[0205] In this embodiment, the power battery can be divided into two parts. A high-voltage harness (i.e., the third connecting line 6) is led out from a certain number of cells in the middle of the power battery. This high-voltage harness divides the power battery into two parts: the part with a higher potential, connected to the positive terminal of the power battery, is the upper battery pack, and the part with a lower potential, connected to the negative terminal of the battery pack, is the lower battery pack. The upper battery pack can be the first sub-battery pack 1, and the lower battery pack can be the second sub-battery pack 2. The positive and negative terminals of the power battery are connected to the positive and negative terminals of the motor controller 3 via the first connecting line 4 and the second connecting line 5, respectively. A high-voltage contactor is connected to the three-phase line N of the motor, so that the high-voltage harness serves as the motor's neutral line.

[0206] Both the upper and lower battery pack high-voltage circuits contain at least one current sampling sensor for the battery management controller to collect high-voltage circuit current. If each battery pack has one current sampling sensor (A1 and A2) on its high-voltage circuit, the motor neutral circuit may not contain a current sampling sensor. If the upper battery pack has one current sampling sensor (A1) on its high-voltage circuit and the lower battery pack has no current sampling sensor, the motor neutral circuit may contain one current sampling sensor (A3). If the upper battery pack has no current sampling sensor but the lower battery pack has one current sampling sensor (A2) on its high-voltage circuit, the motor neutral circuit may contain one current sampling sensor (A3). According to Kirchhoff's laws, with the same current direction, A3 = A1 + A2.

[0207] In one feasible implementation, the selection of current sampling sensors includes, but is not limited to, current Hall sensors and shunts.

[0208] In one feasible implementation, the current sampling sensor is arranged in the upper and lower battery packs, including but not limited to, between the power battery and the battery cell; the current sampling sensor is arranged in the motor neutral circuit, including but not limited to, the left or right side of the high-voltage contactor.

[0209] In one feasible implementation, the type of power battery includes, but is not limited to, lithium iron phosphate batteries, ternary batteries under different systems, etc.

[0210] Figure 7 This is a block diagram illustrating a state-of-charge determination device according to an exemplary embodiment. Figure 7 As shown, the state of charge determination device 700 may include a processor 701 and a memory 702. The state of charge determination device 700 may also include one or more of a multimedia component 703, an input / output interface 704, and a communication component 705.

[0211] The processor 701 controls the overall operation of the state of charge determination device 700 to complete all or part of the steps in the aforementioned state of charge determination method. The memory 702 stores various types of data to support the operation of the state of charge determination device 700. This data may include, for example, instructions for any application or method operating on the state of charge determination device 700, and application-related data such as contact data, sent and received messages, images, audio, video, etc. The memory 702 can be implemented using any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The multimedia component 703 may include a screen and an audio component. The screen may be, for example, a touchscreen, and the audio component is used to output and / or input audio signals. For example, the audio component may include a microphone for receiving external audio signals. The received audio signals may be further stored in the memory 702 or transmitted via the communication component 705. The audio component also includes at least one speaker for outputting audio signals. Input / output interface 704 provides an interface between processor 701 and other interface modules, such as keyboards, mice, and buttons. These buttons can be virtual or physical. Communication component 705 is used for wired or wireless communication between the state-of-charge determination device 700 and other devices. Wireless communication includes, for example, Wi-Fi, Bluetooth, Near Field Communication (NFC), 2G, 3G, 4G, NB-IoT, eMTC, or other 5G technologies, or combinations thereof, and is not limited herein. Therefore, the corresponding communication component 705 may include: a Wi-Fi module, a Bluetooth module, an NFC module, etc.

[0212] In an exemplary embodiment, the state of charge determination device 700 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the state of charge determination method described above.

[0213] In another exemplary embodiment, a computer-readable storage medium including program instructions is also provided, which, when executed by a processor, implement the steps of the state of charge determination method described above. For example, the computer-readable storage medium may be the memory 702 including program instructions described above, which may be executed by the processor 701 of the state of charge determination apparatus 700 to complete the state of charge determination method described above.

[0214] In another exemplary embodiment, a vehicle is also provided, including the battery control system described in the above embodiments, wherein the battery management controller in the battery control system is used for the state of charge determination method described in the above embodiments.

[0215] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0216] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0217] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for determining the state of charge, applied to a power battery, characterized in that, The power battery includes a first sub-battery pack and a second sub-battery pack, and the method includes: After controlling the first sub-battery pack and the second sub-battery pack to perform a first power transfer, the first sub-battery pack and the second sub-battery pack are controlled to perform a second power transfer, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal. The first power transfer between the first sub-battery pack and the second sub-battery pack makes the voltage of a single cell in the first sub-battery pack reach the target voltage range. The state of charge (SOC) of the power battery is defined as the SOC when the SOC of the first sub-battery pack is equal to that of the second sub-battery pack.

2. The method for determining the state of charge according to claim 1, characterized in that, After controlling the first power transfer between the first sub-battery pack and the second sub-battery pack, controlling the second power transfer between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal includes: Control the first power transfer between the first sub-battery pack and the second sub-battery pack, and obtain the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack; Based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, a second power transfer is controlled between the first sub-battery pack and the second sub-battery pack to make the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack equal.

3. The method for determining the state of charge according to claim 2, characterized in that, Before performing a first power transfer between the first sub-battery pack and the second sub-battery pack, and obtaining the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, the method further includes: Obtain the voltage of a single cell in the power battery; The control of the first power transfer between the first sub-battery pack and the second sub-battery pack includes: When the voltage of a single cell in the power battery is within the target plateau range, the first power transfer is controlled between the first sub-battery pack and the second sub-battery pack.

4. The method for determining the state of charge according to claim 2, characterized in that, The step of controlling the first sub-battery pack and the second sub-battery pack to perform a first power transfer, and obtaining the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, includes: Control the first power transfer between the first sub-battery pack and the second sub-battery pack so that the voltage of a single cell in the first sub-battery pack reaches the target voltage range; When the voltage of a single cell in the first sub-battery pack reaches the target voltage range, the target voltage of the single cell in the first sub-battery pack, the first charge change value of the first sub-battery pack, and the second charge change value of the second sub-battery pack are obtained. Based on the target voltage, the first state of charge of the first sub-battery pack is obtained; The second state of charge of the second sub-battery pack is obtained based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery.

5. The method for determining the state of charge according to claim 4, characterized in that, The step of obtaining the first power change value of the first sub-battery pack and the second power change value of the second sub-battery pack includes: The first current of the first sub-battery pack during the first power transfer, the second current of the second sub-battery pack during the first power transfer, and the first duration of the first power transfer are obtained. The product of the first current and the first duration is determined as the first change in charge of the first sub-battery pack, and the product of the second current and the first duration is determined as the second change in charge of the second sub-battery pack.

6. The method for determining the state of charge according to claim 4, characterized in that, The step of obtaining the first state of charge of the first sub-battery pack based on the target voltage includes: Based on the target voltage, the first state of charge is obtained according to the correspondence between the voltage of a single cell in the power battery and the state of charge of the power battery.

7. The method for determining the state of charge according to claim 4, characterized in that, The step of obtaining the second state of charge of the second sub-battery pack based on the first state of charge, the first change in charge value, the second change in charge value, and the total capacity of the power battery includes: The initial state of charge of the first sub-battery pack is obtained based on the first state of charge, the first change in charge value, and the total capacity of the power battery. The second state of charge is obtained based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery.

8. The method for determining the state of charge according to claim 7, characterized in that, Based on the first state of charge, the first change in charge value, and the total capacity of the power battery, the initial state of charge of the first sub-battery pack is obtained, including: When the first sub-battery pack discharges, SOC 上部分初始 =SOC 上部分 +C1 / C0 When the first sub-battery pack is charging, SOC 上部分初始 =SOC 上部分 -C1 / C0 Among them, SOC 上部分初始 The initial state of charge (SOC) of the first sub-cell pack. 上部分 C1 represents the first state of charge of the first sub-battery pack, C0 represents the first change in charge of the first sub-battery pack, and C0 represents the total capacity of the power battery.

9. The method for determining the state of charge according to claim 7, characterized in that, The step of obtaining the second state of charge based on the initial state of charge of the first sub-battery pack, the second change in charge value, and the total capacity of the power battery includes: When the second sub-battery pack is charging, the SOC 下部分 = SOC 上部分初始 +C2 / C0 When the second sub-battery pack discharges, SOC 下部分 = SOC 上部分初始 -C2 / C0 Among them, SOC 下部分 The second state of charge (SOC) of the second sub-cell pack. 上部分初始 C1 represents the initial state of charge of the first sub-battery pack, C2 represents the second change in charge of the second sub-battery pack, and C0 represents the total capacity of the power battery.

10. The method for determining the state of charge according to claim 2, characterized in that, The step of controlling a second power transfer between the first sub-battery pack and the second sub-battery pack based on the first state of charge of the first sub-battery pack and the second state of charge of the second sub-battery pack, so that the state of charge of the first sub-battery pack and the state of charge of the second sub-battery pack are equal, includes: Control the second power transfer between the first sub-battery pack and the second sub-battery pack to obtain the third power change value of the first sub-battery pack and the fourth power change value of the second sub-battery pack; The third state of charge of the first sub-battery pack is obtained based on the first state of charge, the third change in charge value, and the total capacity of the power battery. The fourth state of charge of the second sub-battery pack is obtained based on the second state of charge, the fourth change in charge value, and the total capacity of the power battery. When the third state of charge and the fourth state of charge are equal, the second charge transfer between the first sub-battery pack and the second sub-battery pack is stopped.

11. The method for determining the state of charge according to claim 10, characterized in that, The control of the second power transfer between the first and second sub-battery packs to obtain a third power change value for the first sub-battery pack and a fourth power change value for the second sub-battery pack includes: Control the second power transfer between the first sub-battery pack and the second sub-battery pack, and determine the third current of the first sub-battery pack during the second power transfer, the fourth current of the second sub-battery pack during the second power transfer, and the second duration of the second power transfer. The product of the third current and the second duration is determined as the third change value of the charge of the first sub-battery pack, and the product of the fourth current and the second duration is determined as the fourth change value of the charge of the second sub-battery pack.

12. The method for determining the state of charge according to claim 10, characterized in that, When the first sub-battery pack is charging, the method for calculating the third state of charge is as follows: SOCIETY 上部分 '=SOC 上部分 +C1' / C0 When the first sub-battery pack is charging, the method for calculating the fourth state of charge is as follows: SOC 下部分 '=SOC 下部分 -C2' / C0 Among them, SOC 上部分 'This is the third state of charge, SOC' 下部分 'This is the fourth state of charge, SOC' 上部分 The first state of charge (SOC) of the first sub-cell pack. 下部分 C1' is the second state of charge of the second sub-battery pack, C2' is the third change in charge, C0 is the fourth change in charge, and C0 is the total capacity of the power battery.

13. The method for determining the state of charge according to claim 10, characterized in that, When the first sub-battery pack is discharging, the method for calculating the third state of charge is as follows: SOCIETY 上部分 '= SOC 上部分 -C1' / C0 When the first sub-battery pack is discharging, the method for calculating the fourth state of charge is as follows: SOC 下部分 '= SOC 下部分 +C2' / C0 Among them, SOC 上部分 'This is the third state of charge, SOC' 下部分 'This is the fourth state of charge, SOC' 上部分 The first state of charge (SOC) of the first sub-cell pack. 下部分 C1' is the second state of charge of the second sub-battery pack, C2' is the third change in charge, C0 is the fourth change in charge, and C0 is the total capacity of the power battery.

14. The method for determining the state of charge according to claim 4, characterized in that, Before controlling a first power transfer between the first sub-battery pack and the second sub-battery pack to bring the voltage of a single cell in the first sub-battery pack into a target voltage range, the method further includes: Obtain the temperature of the power battery; Based on the temperature of the power battery, determine the pre-calibrated open-circuit voltage state-of-charge curve, charging voltage state-of-charge curve, and discharging voltage state-of-charge curve corresponding to that temperature. The target voltage range is determined from the charging voltage state-of-charge curve or the discharging voltage state-of-charge curve based on the voltage of a single cell in the power battery and the open-circuit voltage state-of-charge curve.

15. The method for determining the state of charge according to claim 14, characterized in that, The open-circuit voltage state-of-charge curve includes a first voltage rise interval, a second voltage rise interval, and a third voltage rise interval, as well as a first voltage plateau interval and a second voltage plateau interval; the first voltage plateau interval is located between the first voltage rise interval and the second voltage rise interval, the second voltage plateau interval is located between the second voltage rise interval and the third voltage rise interval, and the minimum voltage of the third voltage rise interval is greater than the maximum voltage of the first voltage rise interval. The step of determining the target voltage range from the charging voltage state-of-charge curve or the discharging voltage state-of-charge curve based on the voltage of a single cell in the power battery and the open-circuit voltage state-of-charge curve includes: When the voltage of a single cell in the power battery is in the first voltage plateau period range, the state of charge range corresponding to the first voltage rise range on the open circuit voltage state of charge curve is determined, and the target voltage range is determined according to the voltage range corresponding to the discharge voltage state of charge curve based on the state of charge range. When the voltage of a single cell in the power battery is in the second voltage plateau period range, the third voltage rise range is determined to be the state of charge range corresponding to the open circuit voltage state of charge curve, and the target voltage range is determined according to the voltage range corresponding to the charging voltage state of charge curve.

16. The method for determining the state of charge according to claim 3, characterized in that, After obtaining the voltage of a single cell in the power battery, the method further includes: When the voltage of a single cell in the power battery is in a non-target plateau range, the state of charge of the power battery is determined according to the correspondence between the voltage of the single cell and the state of charge of the power battery.

17. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method for determining the state of charge as described in any one of claims 1-16.

18. A device for determining the state of charge, characterized in that, include: A memory on which computer programs are stored; A processor for executing the computer program in the memory to implement the steps of the state of charge determination method according to any one of claims 1-16.

19. A battery control system, characterized in that, include: A power battery, comprising a first sub-battery pack and a second sub-battery pack connected in series. A motor controller, which is connected to the first sub-battery pack and the second sub-battery pack respectively; A current acquisition component, which is connected to the first sub-battery pack and the second sub-battery pack respectively; A battery management controller connected to the motor controller and the current acquisition component, the battery management controller being configured to perform the state of charge determination method according to any one of claims 1-16.

20. The battery control system according to claim 19, characterized in that, The first sub-battery pack is connected to the positive terminal of the motor controller via the positive terminal interface of the power battery and a first connecting line; The second sub-battery pack is connected to the negative terminal of the motor controller via the negative terminal interface of the power battery and a second connecting line; The first sub-battery pack and the second sub-battery pack are connected to motor point N via a third connecting line; The current acquisition component includes at least two current sampling sensors, and the current sampling sensors are disposed on any two of the first connecting line, the second connecting line and the third connecting line.

21. A vehicle, characterized in that, The battery control system includes any one of claims 19-20, wherein the battery management controller in the battery control system is used to perform the state of charge determination method according to any one of claims 1-16.

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