Method, apparatus and system for determining state of charge

Abstract

The method, device and system for determining the state of charge can obtain an energy parameter value in a first battery pack (105) within a preset time period when a battery system (100) is in a state of no energy output (high voltage under vehicle), and can determine whether a circulating current or a zero drift current is generated in the first battery pack (105) according to a comparison result of the energy parameter value and a preset energy parameter value, and then more accurately calculate the state of charge in the first battery pack (105) based on the comparison result.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method, apparatus and system for determining the state of charge. Background Technology

[0002] The State of Charge (SOC) of a battery reflects its remaining capacity. An accurate SOC plays an important role in battery power indication, remaining range, overcharge and over-discharge protection, battery balancing, charging control, and battery health prediction.

[0003] However, the current method of calculating SOC has low accuracy. Summary of the Invention

[0004] This application provides a method, apparatus, and system for determining the state of charge.

[0005] On one hand, embodiments of this application provide a method for determining the state of charge, which is applied to a sub-battery management unit that is communicatively connected to a main battery management unit.

[0006] The main battery management unit is used to control the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel.

[0007] Sub-battery management unit, used to control the energy output status of the first battery pack;

[0008] The methods include:

[0009] After receiving the first signal sent by the main battery management unit, the electrical parameter values ​​in the first battery pack are acquired within a preset time period; wherein, the first signal is used to indicate that the battery system is in a state of no energy output;

[0010] The state of charge of the first battery pack is determined based on the comparison between the electrical parameter values ​​and the preset electrical parameter thresholds.

[0011] The method for determining the state of charge provided in this application embodiment can acquire the energy electrical parameter value of the first battery pack within a preset time period when the battery system is in a state of no energy output (high voltage under vehicle). Based on the comparison result of the electrical parameter value and the preset electrical parameter value, it can be determined whether the current generated in the first battery pack is a circulating current or a zero drift current, and then the state of charge of the battery pack can be determined more accurately based on the comparison result.

[0012] In one possible implementation, after receiving a first signal from the main battery management unit, the electrical parameter values ​​of the first battery pack are acquired within a preset time period, including: after receiving the first signal from the main battery management unit, controlling the first battery pack to be in an energy output state within a preset time period; the preset time period is determined based on the duration of circulating current within the first battery pack; and acquiring the electrical parameter values ​​of the first battery pack within the preset time period.

[0013] With this technical solution, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energetic state, that is, a current loop is formed in the first battery pack. This can avoid the situation where the voltage difference between parallel battery packs increases due to frequent cutting off of the internal current loop, thus avoiding the formation of large circulating current impacts, thereby avoiding adverse effects on the safety of the battery system.

[0014] In one possible implementation, the first state of charge value of the first battery pack is calculated based on the comparison result between the electrical parameter value and the preset electrical parameter threshold, including: if the electrical parameter value is greater than the preset electrical parameter threshold, the first state of charge value of the first battery pack is calculated based on the electrical parameter value.

[0015] In one possible implementation, the state of charge of the first battery pack is determined based on a comparison between electrical parameter values ​​and preset electrical parameter thresholds, including:

[0016] When the electrical parameter value is less than the preset electrical parameter threshold, the first state of charge value of the first battery pack is calculated based on the preset electrical parameter reference value;

[0017] The state of charge of the first battery pack is determined based on the first state of charge value.

[0018] By using the above-described technical solution, the actual current situation (circulating current or zero drift current) in the first battery pack is determined based on the different comparison results between the electrical parameter values ​​and the preset electrical parameter values. Then, different calculation methods are used to calculate the first state of charge value, resulting in a more accurate SOC calculation result.

[0019] In one possible implementation, determining the state of charge (SOC) of the first battery pack based on the first SOC value includes: subtracting the first SOC value from a preset error value to obtain a second SOC value, wherein the preset error value includes a preset power consumption of the sub-battery management unit; and determining the SOC corresponding to the second SOC value as the SOC of the first battery pack.

[0020] After calculating the first state of charge value based on the current in the first battery pack, the first state of charge is corrected using error values ​​such as the power consumption of the preset sub-battery management unit, thereby obtaining an accurate state of charge for the first battery pack.

[0021] Secondly, embodiments of this application provide a sub-battery management unit that is communicatively connected to a main battery management unit.

[0022] The main battery management unit is used to control the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel.

[0023] Sub-battery management unit, used to control the energy output status of the first battery pack;

[0024] The device includes:

[0025] The acquisition module is used to acquire electrical parameter values ​​in the first battery pack within a preset time period after receiving a first signal sent by the main battery management unit; wherein, the first signal is used to indicate that the battery system is in a state of no energy output;

[0026] The determination module is used to determine the state of charge of the first battery pack based on the comparison results of the electrical parameter values ​​and the preset electrical parameter thresholds.

[0027] Thirdly, embodiments of this application provide an electronic device, which includes a memory and a processor; the memory is used to store executable program code;

[0028] The processor is used to read executable program code stored in memory to execute the method for determining the state of charge in the first aspect.

[0029] Fourthly, embodiments of this application provide a computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the method for determining the state of charge in the first aspect.

[0030] Fifthly, embodiments of this application provide a battery management system, which includes a main battery management unit and a sub-battery management unit.

[0031] The main battery management unit communicates with the sub-battery management unit and is used to control the energy output state of the battery system; the battery system includes a first battery pack and a second battery pack connected in parallel.

[0032] Sub-battery management unit, used to control the energy output status of the first battery pack;

[0033] The sub-battery management unit is also used to execute the method for determining the state of charge in the first aspect. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a battery system disclosed in one embodiment of this application;

[0036] Figure 2 This is a schematic flowchart of a method for determining the state of charge disclosed in an embodiment of this application;

[0037] Figure 3 This is a schematic flowchart of a method for determining the state of charge disclosed in an example of this application;

[0038] Figure 4 This is a schematic flowchart of a method for determining the state of charge disclosed in another example of this application;

[0039] Figure 5 This is a schematic flowchart of a method for determining the state of charge disclosed in another example of this application;

[0040] Figure 6 This is a schematic diagram of the structure of a device for determining the state of charge disclosed in an embodiment of this application;

[0041] Figure 7 This is a schematic diagram of the hardware structure of an electronic device disclosed in an embodiment of this application.

[0042] The accompanying drawings are not drawn to scale.

[0043] Marker explanation:

[0044] 100 - Battery system; 101 - Charging main circuit; 102 - Input terminal; 1021 - Positive terminal; 1022 - Negative terminal; 103 - Output terminal; 104 - Main battery management unit; 105 - First battery pack; 106 - Second battery pack; 107 - Charging branch; 1081 - Positive terminal; 1082 - Negative terminal; 109 - Sub-battery management unit. Detailed Implementation

[0045] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0046] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0047] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] Currently, most battery systems on the market are of a single-level architecture, meaning that a battery system generally includes individual battery packs connected in series. The intelligent management of the battery system is achieved through a Battery Management System (BMS) set up within the system. After the vehicle is powered off, the BMS in the battery system controls the current loop within each individual battery pack to disconnect and collects the zero-drift current when the battery pack switches to the disconnected state to calculate the SOC (State of Charge).

[0049] Because the capacity of a primary architecture battery system is relatively low, the applicant of this application has designed a secondary architecture battery system to improve battery capacity. This battery system includes multiple battery packs connected in parallel. The energy output state of a single battery pack is controlled by a slave battery management unit (SBMU), and the energy output state of the battery system is controlled by a master battery management unit (MBMU). The SBMU corresponding to each battery pack is communicatively connected to the MBMU. The SBMU and MBMU constitute the BMS of the battery system.

[0050] When using a two-tier battery system as the vehicle's power source, the State of Charge (SOC) of the battery system is calculated by first calculating the SOC of each battery pack, and then using the SOC of each battery pack as the basis for calculating the SOC of the entire battery system. Calculating the SOC of a single battery pack often requires disconnecting the current loop within that battery pack and collecting the current value when the current loop is open to calculate the SOC.

[0051] However, the inventors of this application have discovered that frequently interrupting the current loop within the battery pack leads to an increase in the voltage difference between parallel battery packs. When the voltage difference is too large, the circulating current generated between the battery packs may impact the components within the battery pack, thereby affecting the safety of the battery pack.

[0052] However, if the current loop in the parallel battery pack is kept open during the SOC calculation process, the current in the current battery pack, regardless of whether it is the actual energy consumption, will be directly used to calculate the SOC. As a result, due to the low accuracy of the current value sampling, the final SOC value will be inaccurate.

[0053] To ensure the accuracy of SOC calculation in a two-level architecture battery system, embodiments of this application provide a method, apparatus, and system for determining the state of charge. The method and apparatus for determining the state of charge in embodiments of this application can be applied to a sub-battery management unit in a two-level architecture battery system.

[0054] The battery system involved in the implementation of this application will be described below with reference to the accompanying drawings.

[0055] For example, Figure 1 A schematic diagram of a two-level architecture battery system is shown.

[0056] like Figure 1 As shown, the battery system 100 includes a charging main circuit 101, which includes multiple sets of power input terminals 102 and a set of power output terminals 103 (each set of output terminals includes a positive terminal and a negative terminal). The multiple sets of power input terminals 102 are connected in parallel to the power output terminals 103, and a first switch module K1 is provided between each set of power input terminals 102 and power output terminals 103. The main battery control unit 104 in the battery system BMS can control the energy output of the battery system 100 by controlling the on / off state of the first switch module K1.

[0057] Each battery pack (105, 106) connected in parallel in the battery system 100 includes a charging branch. Taking the charging branch 107 in the first battery pack 105 as an example, the charging branch 107 includes a power module E1, a protection module S1, and a second switch module K2. The protection module S1, the power module E1, and the second switch module K2 are connected in series and then connected to the positive and negative output terminals (1081, 1082) of the first battery pack 105. The positive and negative output terminals (1081, 1082) of the first battery pack 105 are connected to one set of power input terminals (1021, 1022) on the charging trunk line 101. The sub-battery management unit 109 corresponding to the first battery pack 105 controls the energy output within the first battery pack 105 by controlling the on / off state of the second switch module K2.

[0058] For example, the first switch module K1 and the second switch module K2 can both be relays, the protection module S1 can be a fuse, and the power module E1 can be a battery cell.

[0059] For example, in a battery system, the entirety of a single battery pack can be referred to as a battery. In terms of battery type, the battery can be any type of battery, including but not limited to: lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, lead-acid batteries, nickel-metal hydride batteries, or lithium-air batteries, etc.

[0060] Optionally, the entire battery system can be housed in a Battery Disconnect Unit (BDU).

[0061] Optionally, a voltage converter (not shown in the figure) is also connected to the charging branch in the first battery pack. The voltage converter is used to convert the high voltage output by the charging branch into a low voltage to power the corresponding sub-battery management unit.

[0062] It should be understood that the first battery pack also includes a sampling module (not shown in the figure). The sampling module is used to collect the electrical parameter values ​​on the charging branch within the first battery pack and transmit them to the corresponding sub-battery management unit. Optionally, the sampling module can be an open / closed-loop Hall element, a fluxgate, or a Shunt shunt, capable of collecting the current value on the charging branch.

[0063] It should be understood that battery packs in a battery system can all have such... Figure 1 The structure of the first battery pack shown is illustrated.

[0064] It should be understood that the aforementioned battery system may be a battery system in electric vehicles (including pure electric vehicles and plug-in hybrid electric vehicles) or a battery system in other application scenarios.

[0065] Figure 2A flowchart illustrating a method for determining the state of charge (SOC) according to one embodiment of this application is shown. This determination method can be applied to a sub-battery management unit, wherein the sub-battery management unit is communicatively connected to a main battery management unit. The main battery management unit controls the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel. The sub-battery management unit controls the energy output state of the first battery pack.

[0066] like Figure 2 As shown, the method may include steps S201 to S203:

[0067] S201. After receiving the first signal sent by the main battery management unit, acquire the electrical parameter values ​​in the first battery pack within a preset time period; wherein, the first signal is used to characterize that the battery system is in a state of no energy output.

[0068] After the vehicle loses power, the VCU (Vehicle Control Unit) sends the power-off information to the MBMU. The MBMU then switches the battery system to a no-energy-output state and transmits the first signal representing this state to the SBMU corresponding to the first battery pack.

[0069] When the SBMU receives the first signal, it acquires the electrical parameter values ​​of the first battery pack from the sampling unit within the first battery pack within a preset time period.

[0070] Optionally, this electrical parameter value can be a current value.

[0071] S202. Determine the state of charge of the first battery pack based on the comparison results between the electrical parameter values ​​and the preset electrical parameter thresholds.

[0072] The preset electrical parameter threshold is used to distinguish whether the current in the battery pack is circulating current or zero drift current.

[0073] During the operation of parallel battery packs in a two-level architecture current system, if there is a voltage difference between the battery packs, a phenomenon will occur where the battery pack with higher voltage charges the battery pack with lower voltage. The current in this phenomenon is called circulating current. When the vehicle is powered off, the instantaneous voltage difference between the battery packs will cause instantaneous circulating current within the battery packs. In the embodiments of this application, when calculating the State of Charge (SOC), the circulating current is the actual energy consumption.

[0074] The zero-drift current within the battery pack is the current that causes zero-point drift. Zero-point drift occurs when the input signal to the amplifier circuit is zero (i.e., no AC input), and due to factors such as changes in ambient temperature and unstable power supply voltage, the static operating point changes and is amplified and transmitted stage by stage, causing the output voltage of the circuit to deviate from its original fixed value and fluctuate. In this embodiment, the zero-drift current is not considered as actual energy consumption when calculating the State of Charge (SOC).

[0075] Zero drift current is smaller than circulating current. Therefore, in this embodiment, zero drift current and circulating current can be distinguished by a preset threshold value of electrical parameters.

[0076] After the SBMU obtains the electrical parameter values ​​in the first battery pack, it first compares them with the preset electrical parameter thresholds to determine whether the electrical parameter value is a circulating current value or a zero drift current value, that is, to determine whether there is actual energy consumption in the first battery pack. Based on the comparison results, the state of charge of the first battery pack can be determined accordingly, thus improving the accuracy of the calculation of the state of charge value.

[0077] Figure 3 A flowchart illustrating a method for determining the state of charge in one example of this application is shown.

[0078] To ensure battery pack safety while accurately calculating SOC, optional measures include... Figure 3 As shown in this embodiment, after receiving the first signal sent by the main battery management unit in step S201, the acquisition of electrical parameter values ​​in the first battery pack within a preset time period may specifically include steps S301 to S302:

[0079] S301. After receiving the first signal sent by the main battery management unit, control the first battery pack to be in an energy output state within a preset time period;

[0080] S302. Within a preset time period, obtain the electrical parameter values ​​of the first battery pack.

[0081] like Figure 3 As shown, when the vehicle is powered off by high voltage, the MBMU cuts off the external energy output of the battery system through step S300 and sends a first signal to the SBMU corresponding to the first battery pack. At this time, the entire battery system has no external energy output, but there may be a momentary current in the first battery pack. Therefore, after receiving the first signal, the SBMU corresponding to the first battery pack controls the current loop (charging branch) in the first battery pack to remain open through step S301, so as to avoid the momentary current from impacting the switching module on the branch due to the operation of cutting off the charging branch, thereby affecting the safety of the battery pack.

[0082] The preset duration is determined based on the duration of circulating current within the first battery pack. For example, the duration of circulating current within the corresponding battery pack can be determined through a preset number of tests, and the average or maximum value of this duration can be calculated as the preset duration.

[0083] Within a preset time period, the current present in the first battery pack may be a circulating current or a zero-drift current, which can be determined by the electrical parameter values ​​of the first battery pack collected in step S302.

[0084] After a preset time, the second switch module on the charging branch of the first battery pack can be switched to the open state, or it can remain closed.

[0085] In this embodiment, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energy output state, that is, a current loop is formed in the first battery pack. This can avoid the situation where the voltage difference between parallel battery packs increases due to frequent cutting off of the internal current loop, thus avoiding adverse effects on the safety of the battery system.

[0086] Figure 4 A flowchart illustrating a method for determining the state of charge in another example of this application is shown.

[0087] To accurately determine whether the current within the battery pack is circulating current or zero-drift current, and thus accurately calculate the State of Charge (SOC) within the battery pack, options include, for example... Figure 4 As shown, step S202 determines the state of charge of the first battery pack based on the comparison result between the electrical parameter values ​​and the preset electrical parameter thresholds, which may specifically include S401 to S404:

[0088] S401. Compare the electrical parameter values ​​with the preset electrical parameter thresholds;

[0089] S402. When the electrical parameter value is greater than the preset electrical parameter threshold, calculate the first state of charge value of the first battery pack based on the electrical parameter value;

[0090] S403. When the electrical parameter value is less than the preset electrical parameter threshold, calculate the first state of charge value of the first battery pack according to the preset electrical parameter reference value;

[0091] S404. Determine the state of charge of the first battery pack based on the first state of charge value.

[0092] The preset electrical parameter value is a reference current value that can determine whether the current instantaneous current in the battery pack is a circulating current or a zero drift current. Optionally, in this embodiment, the preset electrical parameter value is 300mA. The electrical parameter value below 300mA is the zero drift current value, and the electrical parameter value above 300mA is the circulating current value.

[0093] After comparing the values ​​in step S401, if the electrical parameter value of the first battery pack is greater than the preset electrical parameter value, it can be determined that the current in the current battery pack is circulating current, that is, it can be determined that there is real power consumption in the current battery pack. Then, in step S402, the SOC of the first battery pack can be calculated based on the corresponding collected electrical parameter value.

[0094] Conversely, if the electrical parameter value of the first battery pack is less than the preset electrical parameter value, it can be determined that the current in the current battery pack is zero drift current, that is, it can be determined that there is no real power consumption in the current battery pack. Then, the SOC of the first battery pack can be calculated directly based on the preset electrical parameter reference value through step S403.

[0095] Optionally, the preset electrical parameter value is 0, which means that there is no actual current consumption in the current battery pack.

[0096] Optionally, when calculating SOC using electrical parameter values ​​or electrical parameter reference values, it can be calculated using the ampere-hour integration method or other suitable calculation methods. This application does not limit the specific implementation of the embodiments.

[0097] In this embodiment, the actual current situation (circulating current or zero drift current) in the first battery pack is determined based on the different comparison results between the electrical parameter values ​​and the preset electrical parameter values. Thus, different calculation methods can be used to calculate the first state of charge value, and a more accurate SOC calculation result can be obtained.

[0098] After calculating the first state of charge value, the state of charge of the corresponding battery pack can be determined through step S404. Since the first state of charge value is calculated based on the actual energy consumption in the battery pack, it is highly accurate.

[0099] Figure 5 A schematic flowchart illustrating the method for determining the state of charge in yet another example of this application is shown.

[0100] To obtain a more accurate SOC, optionally, in the embodiments of this application, such as Figure 5 As shown, step S404 determines the state of charge of the first battery pack based on the first state of charge value, which may specifically include S501 to S502:

[0101] S501. Subtract the first state of charge value from the preset error value to obtain the second state of charge value;

[0102] S502. Determine the state of charge corresponding to the second state of charge value as the state of charge of the first battery pack.

[0103] Since other components in the first battery pack may still consume power after the battery system is in a state of no energy output, the first state of charge value can be corrected by using the corresponding preset error value, thereby determining a more accurate state of charge of the first battery pack.

[0104] Optionally, the preset error value may include the power consumption of the sub-battery management unit, and may also include the power consumption of other components in the battery pack.

[0105] Because some components in the battery pack consume electrical energy when the charging branch is in the on-line state within a preset time period, the calculated SOC may have a certain error. Therefore, in this embodiment, the power consumption of the consuming components is used as the error value. The first state of charge value is corrected in step S501, and a second state of charge value is obtained after correction. In step S502, the second state of charge value is determined as the true state of charge of the first battery pack, resulting in a more accurate state of charge determination result.

[0106] The sub-battery management unit can send the calculated second state of charge value to the main battery management unit. The main battery management unit then calculates the state of charge of the entire battery system based on the second state of charge value of the first battery pack and the second state of charge values ​​of other batteries.

[0107] The method for calculating the state of charge of a battery system is a mature technology in this field and will not be elaborated here.

[0108] The sub-cell management unit of the first battery pack can determine the SOC of the first battery pack using the method described in this application embodiment. Similarly, the sub-cell management units of other battery packs in the battery system can also determine the SOC of their respective battery packs using the method described in this application embodiment. The sub-cell management units of each battery pack transmit the determined SOC value (second state of charge value) to the main battery management unit. The main battery management unit can calculate the SOC of the entire battery system based on the received SOC values ​​of each battery pack. Since the SOC values ​​of each battery pack are highly accurate, the accuracy of the SOC calculation of the battery system is improved.

[0109] Figure 6 The illustration shows a schematic diagram of a device for determining the state of charge (SOC) according to an embodiment of this application. This device can be applied to a sub-battery management unit, which is communicatively connected to a main battery management unit. The main battery management unit controls the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel. The sub-battery management unit controls the energy output state of the first battery pack.

[0110] like Figure 6 As shown, the device may include:

[0111] The acquisition module 601 is used to acquire electrical parameter values ​​in the first battery pack within a preset time period after receiving a first signal sent by the main battery management unit; wherein, the first signal is used to indicate that the battery system is in a state of no energy output;

[0112] The determination module 602 is used to determine the state of charge of the first battery pack based on the comparison result between the electrical parameter values ​​and the preset electrical parameter thresholds.

[0113] Optionally, the battery system involved in the embodiments of this application may have the following characteristics: Figure 1 The structure of the two-level architecture battery system shown is not described in detail here.

[0114] After the vehicle loses power, the VCU (Vehicle Control Unit) sends the power-off information to the MBMU. The MBMU then switches the battery system to a no-energy-output state and transmits the first signal representing this state to the SBMU corresponding to the first battery pack.

[0115] When the SBMU receives the first signal, it acquires the electrical parameter values ​​of the first battery pack from the sampling unit within the first battery pack within a preset time period.

[0116] Optionally, this electrical parameter value can be a current value.

[0117] The preset electrical parameter threshold is used to distinguish whether the current in the battery pack is circulating current or zero drift current.

[0118] During the operation of parallel battery packs in a two-level architecture current system, if there is a voltage difference between the battery packs, a phenomenon will occur where the battery pack with higher voltage charges the battery pack with lower voltage. The current in this phenomenon is called circulating current. When the vehicle is powered off, the instantaneous voltage difference between the battery packs will cause instantaneous circulating current within the battery packs. In the embodiments of this application, when calculating the State of Charge (SOC), the circulating current is the actual energy consumption.

[0119] The zero-drift current within the battery pack is the current that causes zero-point drift. Zero-point drift occurs when the input signal to the amplifier circuit is zero (i.e., no AC input), and due to factors such as changes in ambient temperature and unstable power supply voltage, the static operating point changes and is amplified and transmitted stage by stage, causing the output voltage of the circuit to deviate from its original fixed value and fluctuate. In this embodiment, the zero-drift current is not considered as actual energy consumption when calculating the State of Charge (SOC).

[0120] Zero drift current is smaller than circulating current. Therefore, in this embodiment, zero drift current and circulating current can be distinguished by a preset threshold value of electrical parameters.

[0121] After the SBMU obtains the electrical parameter values ​​in the first battery pack, it first compares them with the preset electrical parameter thresholds to determine whether the electrical parameter value is a circulating current value or a zero drift current value, that is, to determine whether there is actual energy consumption in the first battery pack. Based on the comparison results, the state of charge of the first battery pack can be determined accordingly, thereby improving the accuracy of the calculation of the state of charge value.

[0122] Since other components in the first battery pack may still consume power after the battery system is in a state of no energy output, the first state of charge value can be corrected according to the corresponding preset error value, thereby determining a more accurate state of charge of the first battery pack.

[0123] Optionally, in order to ensure the safety of the battery pack while accurately calculating the SOC, in this embodiment of the application, the acquisition module 601 may specifically include:

[0124] The control submodule 6011 is used to control the first battery pack to be in an energy output state within a preset time after receiving the first signal sent by the main battery management unit.

[0125] The acquisition submodule 6012 is used to acquire the electrical parameter values ​​of the first battery pack within a preset time period.

[0126] When the vehicle is powered off, the MBMU cuts off the battery system's external energy output and sends a first signal to the SBMU corresponding to the first battery pack. At this time, the entire battery system has no external energy output, but there may be a momentary current in the first battery pack. Therefore, after receiving the first signal, the SBMU corresponding to the first battery pack controls the current loop (charging branch) in the first battery pack to remain open, preventing the momentary current from impacting the switching module on that branch and thus affecting the safety of the battery pack.

[0127] The preset duration is determined based on the duration of circulating current within the first battery pack.

[0128] Within a preset time period, the current present in the first battery pack may be either circulating current or zero drift current, which can be determined by collecting the electrical parameter values ​​of the first battery pack.

[0129] After a preset time, the second switch module on the charging branch of the first battery pack can be switched to the open state, or it can remain closed.

[0130] In this embodiment, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energy output state, that is, a current loop is formed in the first battery pack. This can avoid the situation where the voltage difference between parallel battery packs increases due to frequent cutting off of the internal current loop, thus avoiding adverse effects on the safety of the battery system.

[0131] To accurately determine whether the current in the battery pack is circulating current or zero-drift current, and thus accurately calculate the SOC (State of Charge) in the battery pack, the determining module 602 may optionally include:

[0132] Comparison module 6021 is used to compare electrical parameter values ​​with preset electrical parameter values;

[0133] The first calculation submodule 6022 is used to calculate the first state of charge value of the first battery pack based on the electrical parameter value when the electrical parameter value is greater than the preset electrical parameter threshold.

[0134] The second calculation submodule 6023 is used to calculate the first state of charge value of the first battery pack based on the preset electrical parameter reference value when the electrical parameter value is less than the preset electrical parameter threshold.

[0135] The determination submodule 6024 is used to determine the state of charge of the first battery pack based on the first state of charge value.

[0136] The preset electrical parameter value is a reference current value that can determine whether the current instantaneous current in the battery pack is a circulating current or a zero drift current. Optionally, in this embodiment, the preset electrical parameter value is 300mA. The electrical parameter value below 300mA is the zero drift current value, and the electrical parameter value above 300mA is the circulating current value.

[0137] If the electrical parameter value of the first battery pack is greater than the preset electrical parameter value, it can be determined that the current in the current battery pack is circulating current, that is, it can be determined that there is real power consumption in the current battery pack, and the SOC of the first battery pack can be calculated based on the corresponding collected electrical parameter value.

[0138] Conversely, if the electrical parameters of the first battery pack are less than the preset electrical parameter values, it can be determined that the current in the current battery pack is zero-drift current, that is, it can be determined that there is no actual power consumption in the current battery pack. In this case, the SOC of the first battery pack is directly calculated based on the preset electrical parameter benchmark value. Here, the preset electrical parameter value of 0 indicates that there is no actual current consumption in the current battery pack.

[0139] Optionally, when calculating SOC using electrical parameter values ​​or electrical parameter reference values, it can be calculated using the ampere-hour integration method or other suitable calculation methods. This application does not limit the specific implementation of the embodiments.

[0140] In this embodiment, the actual current situation (circulating current or zero drift current) in the first battery pack is determined based on the different comparison results between the electrical parameter values ​​and the preset electrical parameter values. Thus, different calculation methods can be used to calculate the first state of charge value, and a more accurate SOC calculation result can be obtained.

[0141] After calculating the first state of charge value, the state of charge of the corresponding battery pack can be determined by the determination submodule 6024. Since the first state of charge value is calculated based on the actual energy consumption in the battery pack, it is highly accurate.

[0142] To obtain a more accurate SOC, optionally, in this embodiment of the application, the determining submodule 6024 can be specifically used for:

[0143] The second state of charge value is obtained by subtracting the first state of charge value from the preset error value.

[0144] The state of charge corresponding to the second state of charge value is determined as the state of charge of the first battery pack.

[0145] Since other components in the first battery pack may still consume power after the battery system is in a state of no energy output, the first state of charge value can be corrected by using the corresponding preset error value, thereby determining a more accurate state of charge of the first battery pack.

[0146] Optionally, the preset error value may include the power consumption of the sub-battery management unit, and may also include the power consumption of other components in the battery pack.

[0147] Because some components in the battery pack consume electrical energy when the charging branch is in the on-line state within a preset time period, the calculated SOC may have some error. Therefore, in this embodiment, the power consumption of the consuming components is used as the error value to correct the first state of charge value, thereby obtaining an accurate state of charge for the first battery pack.

[0148] The sub-battery management unit of the first battery pack can determine the SOC of the first battery pack using the method described in this application embodiment. Similarly, the sub-battery management units of other battery packs in the battery system can also determine the SOC of their respective battery packs using the method described in this application embodiment. The sub-battery management units of each battery pack transmit the determined SOC value (second state of charge value) to the main battery management unit. The main battery management unit can calculate the SOC of the entire battery system based on the received SOC values ​​of each battery pack. Since the SOC values ​​of each battery pack are highly accurate, the accuracy of the SOC calculation of the battery system is improved.

[0149] Figure 7 A schematic diagram of the hardware structure of an electronic device according to an embodiment of this application is shown. Figure 7 As shown, the electronic device 700 includes a memory 701 and a processor 702; the memory 702 is used to store executable program code;

[0150] The processor 701 is used to read the executable program code stored in the memory 702 to execute the various processes of the above-described method embodiment for determining the state of charge, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0151] This application provides a readable storage medium including instructions. When the instructions are executed on a processor, they can implement the various processes of the above-described method for determining the state of charge and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0152] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes a computer-readable storage medium, such as a read-only memory (ROM) or a random access memory (RAM).

[0153] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface and the processor are coupled. The processor is used to run programs or instructions to implement the various processes of the above-described method embodiment for determining the state of charge, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0154] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0155] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for determining the state of charge, the method being applied to a sub-battery management unit, the sub-battery management unit being communicatively connected to a main battery management unit. The main battery management unit is used to control the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel. The sub-battery management unit is used to control the energy output state of the first battery pack; The method includes: Upon receiving the first signal sent by the main battery management unit, the electrical parameter values ​​of the first battery pack are acquired within a preset time period; wherein, the first signal is used to indicate that the battery system is in a state of no energy output; Based on the comparison between the electrical parameter values ​​and the preset electrical parameter threshold, the state of charge of the first battery pack is determined. The preset electrical parameter threshold is used to distinguish whether the current in the battery pack is circulating current or zero drift current. Circulating current is the actual energy consumption, while zero drift current is not considered as actual energy consumption.

2. The method according to claim 1, wherein, After receiving the first signal sent by the main battery management unit, the step of acquiring the electrical parameter values ​​of the first battery pack within a preset time period includes: Upon receiving the first signal sent by the main battery management unit, the first battery pack is controlled to be in an energy output state within a preset duration; the preset duration is the expected duration of circulating current within the first battery pack. Within the preset time period, the electrical parameter values ​​of the first battery pack are acquired.

3. The method according to claim 1, wherein, Determining the state of charge of the first battery pack based on the comparison result between the electrical parameter values ​​and the preset electrical parameter thresholds includes: If the electrical parameter value is greater than a preset electrical parameter threshold, the first state of charge value of the first battery pack is calculated based on the electrical parameter value. The state of charge of the first battery pack is determined based on the first state of charge value.

4. The method according to claim 1, wherein, Determining the state of charge of the first battery pack based on the comparison result between the electrical parameter values ​​and the preset electrical parameter thresholds includes: When the electrical parameter value is less than a preset electrical parameter threshold, the first state of charge value of the first battery pack is calculated based on the preset electrical parameter reference value. The state of charge of the first battery pack is determined based on the first state of charge value.

5. The method according to claim 3 or 4, wherein, Determining the state of charge of the first battery pack based on the first state of charge value includes: The second state of charge value is obtained by subtracting the first state of charge value from the preset error value, wherein the preset error value includes the preset power consumption of the sub-battery management unit. The state of charge corresponding to the second state of charge value is determined as the state of charge of the first battery pack.

6. A device for determining the state of charge, the device being applied to a sub-battery management unit, the sub-battery management unit being communicatively connected to a main battery management unit. The main battery management unit is used to control the energy output state of the battery system, which includes at least a first battery pack and a second battery pack connected in parallel. The sub-battery management unit is used to control the energy output state of the first battery pack; The device includes: The acquisition module is used to acquire electrical parameter values ​​in the first battery pack within a preset time period after receiving a first signal sent by the main battery management unit; wherein, the first signal is used to indicate that the battery system is in a state of no energy output; The determination module is used to determine the state of charge of the first battery pack based on the comparison result between the electrical parameter values ​​and the preset electrical parameter threshold. The preset electrical parameter threshold is a threshold used to distinguish whether the current in the battery pack is circulating current or zero drift current. Circulating current is the actual energy consumption, while zero drift current is not considered as actual energy consumption.

7. An electronic device, the device comprising a memory and a processor; the memory being used to store executable program code; The processor is used to read executable program code stored in the memory to execute the method for determining the state of charge as described in any one of claims 1 to 5.

8. A readable storage medium comprising instructions that, when executed on a processor, implement the method for determining the state of charge as described in any one of claims 1 to 5.

9. A battery system comprising a plurality of battery packs connected in parallel, the battery system further comprising a battery management system. The battery management system includes a main battery management unit and multiple sub-battery management units. The main battery management unit is communicatively connected to the sub-battery management unit and is used to control the energy output state of the battery system; Multiple sub-battery management units are used to control the energy output state of multiple battery packs in a one-to-one correspondence; The sub-battery management unit is further configured to perform the method for determining the state of charge as described in any one of claims 1-5.

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