Method for predicting state of charge of battery pack, battery pack, and storage medium

Abstract

The application discloses a battery pack state of charge prediction method, a battery pack and a computer readable storage medium. The method comprises the following steps: obtaining a static temperature value of the battery pack after the battery pack is discharged to a load device for a preset time length; determining a voltage change rate of the battery pack within the preset time length; and predicting the state of charge of the battery pack according to the static temperature value and the voltage change rate. The method can greatly shorten the static time, solve the problem of low accuracy and efficiency caused by the long static time of the battery pack in the related art, and effectively improve the efficiency and accuracy of the prediction of the state of charge of the battery pack.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a method for predicting the state of charge of a battery pack, a battery pack, and a computer-readable storage medium. Background Technology

[0002] The open-circuit voltage method is a common method for predicting the state of charge (SOC) of a battery pack. The working principle of the open-circuit voltage method is based on the relatively fixed functional relationship between open-circuit voltage and SOC, under conditions of prolonged inactivity of the battery pack. Since open-circuit voltage is difficult to stabilize in a short period, the battery pack must be allowed to rest for an extended period before it can be used to predict the battery's SOC. In practical applications, due to frequent starts-ups of load devices, it is difficult for battery packs to meet the long-term inactivity requirement of the open-circuit voltage method, resulting in low accuracy and efficiency in predicting SOC.

[0003] Therefore, improving the efficiency and accuracy of predicting the state of charge of battery packs has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a method for predicting the state of charge (SOC) of a battery pack, a battery pack, and a computer-readable storage medium. By predicting the SOC of the battery pack based on the temperature value and voltage change rate after the battery pack has been left to stand for a preset period of time after discharge, the standing time can be significantly shortened. This solves the problem in related technologies where predicting the SOC based on the open-circuit voltage method requires a long period of standing of the battery pack, resulting in low accuracy and efficiency. This method can effectively improve the efficiency and accuracy of predicting the SOC of the battery pack.

[0005] In a first aspect, this application provides a method for predicting the state of charge of a battery pack, applied to a battery pack, the method comprising:

[0006] Obtain the settling temperature value of the battery pack after it has been left to stand for a preset time after discharging the load device; determine the voltage change rate of the battery pack during the preset time; and predict the state of charge of the battery pack based on the settling temperature value and the voltage change rate.

[0007] Secondly, this application also provides a battery pack, the battery pack including a memory and a processor;

[0008] The memory is used to store computer programs;

[0009] The processor is configured to implement the battery pack state of charge prediction method as described above when executing the computer program.

[0010] Thirdly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for predicting the state of charge of a battery pack as described above.

[0011] This application discloses a method for predicting the state of charge (SOC) of a battery pack, a battery pack, and a computer-readable storage medium. The method includes: obtaining the settling temperature value of the battery pack after it has been left to stand for a preset time following discharge to a load device; determining the voltage change rate of the battery pack during the preset settling time; and predicting the SOC of the battery pack based on the settling temperature value and the voltage change rate. This application's embodiment predicts the SOC of the battery pack based on the settling temperature value and voltage change rate after the battery pack has been left to stand for a preset time following discharge. This significantly shortens the settling time and solves the problem in related technologies where predicting the SOC based on the open-circuit voltage method requires a long period of battery pack standtling, resulting in low accuracy and efficiency. This method effectively improves the efficiency and accuracy of predicting the SOC of the battery pack. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of a battery pack provided in an embodiment of this application;

[0014] Figure 2 This is a schematic flowchart of a method for predicting the state of charge of a battery pack according to an embodiment of this application;

[0015] Figure 3 This is a schematic flowchart illustrating the determination of voltage change rate provided in an embodiment of this application;

[0016] Figure 4 This is a schematic flowchart illustrating a sub-step for determining the rate of voltage change, provided in an embodiment of this application.

[0017] Figure 5 This is a schematic flowchart illustrating a sub-step for predicting the state of charge of a battery pack, as provided in an embodiment of this application.

[0018] Figure 6 This is a schematic flowchart illustrating another method for predicting the state of charge of a battery pack, as provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0021] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] This application provides a method for predicting the state of charge (SOC) of a battery pack, a battery pack, and a computer-readable storage medium. The method for predicting the SOC of a battery pack can be applied to a battery pack. By predicting the SOC of the battery pack based on the temperature value and voltage change rate after the battery pack has been left to stand for a preset period of time following discharge, the standing time can be significantly shortened. This solves the problem in related technologies where predicting the SOC based on the open-circuit voltage method requires a long period of standing, resulting in low accuracy and efficiency. Therefore, this method can effectively improve the efficiency and accuracy of predicting the SOC of a battery pack.

[0024] For example, the battery pack can be a battery pack in an energy storage device, which can be an energy storage device on a vehicle or a portable energy storage device, without limitation.

[0025] For example, an energy storage device can detect and display the remaining discharge time of a battery pack.

[0026] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a battery pack 1000 provided in an embodiment of this application. The battery pack 1000 may include a processor 1001 and a memory 1002, wherein the processor 1001 and the memory 1002 can be connected via a bus, such as an I / O bus. 2Any applicable bus, such as the C (Inter-integrated Circuit) bus.

[0027] The memory 1002 may include a storage medium and internal memory. The storage medium may store an operating system and a computer program. The computer program includes program instructions that, when executed, cause the processor to perform any method for predicting the state of charge of the battery pack.

[0028] The processor 1001 provides computing and control capabilities to support the operation of the entire battery pack 1000. Of course, the processor 1001 can be built into the battery pack 1000, or it can be the main processor in an energy storage device or a processor in another battery pack.

[0029] The processor 1001 can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0030] In one embodiment, the processor 1001 is configured to run a computer program stored in the memory 1002 to perform the following steps:

[0031] Obtain the settling temperature of the battery pack after it has been discharged from the load device for a preset time; determine the voltage change rate of the battery pack during the preset settling time; and predict the state of charge of the battery pack based on the settling temperature and the voltage change rate.

[0032] In one embodiment, when determining the rate of voltage change of the battery pack during a preset resting period, the processor 1001 is configured to:

[0033] Obtain the initial open-circuit voltage of the battery pack at the end of the discharge to the load device; obtain the target open-circuit voltage of the battery pack after a preset resting time; determine the voltage change rate based on the initial open-circuit voltage, the target open-circuit voltage, and the preset time.

[0034] In one embodiment, when the processor 1001 determines the voltage change rate based on the initial open-circuit voltage, the target open-circuit voltage, and a preset duration, it is used to:

[0035] The open-circuit voltage difference is determined based on the difference between the target open-circuit voltage and the initial open-circuit voltage; the voltage change rate is calculated based on the open-circuit voltage difference and the preset time.

[0036] In one embodiment, the processor 1001, when implementing the prediction of the state of charge of the battery pack based on the resting temperature value and the rate of voltage change, is configured to:

[0037] Based on the preset correspondence between battery temperature and discharge current rate, multiple candidate open-circuit voltage and state of charge (SCC) tables are determined according to the static temperature value. The voltage change rate range in the candidate open-circuit voltage and SCC tables is different for different discharge current rates. The voltage change rate is matched with the voltage change rate range in each candidate open-circuit voltage and SCC table, and the successfully matched candidate open-circuit voltage and SCC tables are determined as the target open-circuit voltage and SCC tables. Based on the target open-circuit voltage and SCC tables, the SCC of the battery pack is determined according to the target open-circuit voltage.

[0038] In one embodiment, the target open-circuit voltage and state of charge relationship table includes multiple open-circuit voltages corresponding to different states of charge; when the processor 1001 determines the state of charge of the battery pack based on the target open-circuit voltage and state of charge relationship table, it is used to:

[0039] Determine the open-circuit voltage range to which the target open-circuit voltage belongs, including the first open-circuit voltage and the second open-circuit voltage; determine the state of charge range corresponding to the open-circuit voltage range, including the first state of charge corresponding to the first open-circuit voltage and the second state of charge corresponding to the second open-circuit voltage; calculate the state of charge corresponding to the target open-circuit voltage based on the open-circuit voltage range and the state of charge range.

[0040] In one embodiment, the processor 1001 is also configured to implement:

[0041] Determine multiple preset battery temperatures and multiple discharge current rates corresponding to each battery temperature; construct a table showing the relationship between open-circuit voltage and state of charge for each battery temperature and multiple discharge current rates.

[0042] In one embodiment, when the processor 1001 constructs a table relating open-circuit voltage to state of charge for multiple discharge current rates corresponding to each battery temperature, it is used to:

[0043] At each battery temperature, the battery pack is controlled to discharge multiple times according to a preset discharge strategy, and the state of charge, open circuit voltage, and voltage change rate corresponding to each discharge are measured. The discharge strategy includes different discharge current ratios and different discharge durations, and the product of the discharge current ratio and the discharge duration is a preset value. Based on the state of charge, open circuit voltage, and voltage change rate corresponding to each discharge, a table of open circuit voltage and state of charge relationship for different discharge current ratios corresponding to each battery temperature is generated.

[0044] In one embodiment, before implementing the control of the battery pack to perform multiple discharges according to a preset discharge strategy at each battery temperature, the processor 1001 is also configured to implement:

[0045] Determine the state of charge (SOC) of the battery pack; if the SOC of the battery pack is less than a preset SOC threshold, charge the battery pack until the SOC of the battery pack is greater than or equal to the SOC threshold.

[0046] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of this application. Unless otherwise specified, the following embodiments and features described herein can be combined with each other. Please refer to... Figure 2 , Figure 2 This is a schematic flowchart illustrating a method for predicting the state of charge of a battery pack, as provided in an embodiment of this application. Figure 2 As shown, the method for predicting the state of charge of a battery pack includes steps S10 to S30.

[0047] Step S10: Obtain the static temperature value of the battery pack after it has been left to stand for a preset time after discharging the load device.

[0048] It should be noted that the battery pack state of charge prediction method provided in this application embodiment can be applied to scenarios where the battery pack has finished discharging the load device. By predicting the battery pack's state of charge based on the temperature value and voltage change rate after the battery pack has been left to stand for a preset time after discharge, the standing time can be significantly shortened. This solves the problem in related technologies where predicting the state of charge based on the open-circuit voltage method requires a long period of standing of the battery pack, resulting in low accuracy and efficiency. It can effectively improve the efficiency and accuracy of predicting the battery pack's state of charge.

[0049] For example, a load device refers to an external electrical appliance. For instance, as opposed to an energy storage device, a load device can be various electrical appliances in a home, or various electronic devices or instruments in a vehicle, etc.

[0050] In some embodiments, the static temperature value of the battery pack after it has been left to stand for a preset period of time after discharging the load device can be obtained. Here, the end of discharging the load device means that the battery pack is disconnected from the load device or the battery pack stops discharging to the load device.

[0051] For example, after the battery pack stops discharging to the load device, the static temperature value of the battery pack is obtained after a preset resting time. For instance, the static temperature value of the battery pack can be obtained through a Battery Management System (BMS).

[0052] It should be noted that the settling temperature value refers to the temperature value of the battery pack after a preset settling time. The preset time can be expressed as t. The preset time can be set according to actual conditions, and the specific value is not limited here. In the embodiments of this application, the preset time is much shorter than the settling time of the open-circuit voltage method in related technologies. For example, the settling time of the open-circuit voltage method can be several times the preset time in the embodiments of this application.

[0053] Step S20: Determine the voltage change rate of the battery pack within a preset resting time.

[0054] It should be noted that the voltage change rate of the battery pack refers to the rate at which the voltage of the battery pack changes within a preset resting time, and is used to measure the rate at which the voltage of the battery pack changes when it is at rest.

[0055] In this embodiment of the application, after the battery pack has finished discharging the load device, the rate of change of voltage of the battery pack during a preset resting period can be determined. The rate of change of voltage can be expressed as dv / dt.

[0056] Step S30: Predict the state of charge of the battery pack based on the static temperature value and voltage change rate.

[0057] In this embodiment of the application, after determining the rate of voltage change of the battery pack within a preset resting time, the state of charge of the battery pack can be predicted based on the resting temperature value and the rate of voltage change.

[0058] The above embodiments predict the state of charge (SOC) of the battery pack based on the temperature value and voltage change rate after the battery pack has been left to stand for a preset time after discharge. This significantly shortens the standing time and solves the problem in related technologies where predicting SOC based on the open-circuit voltage method requires a long period of standing of the battery pack, resulting in low accuracy and efficiency. This can effectively improve the efficiency and accuracy of predicting the SOC of the battery pack.

[0059] In the embodiments of this application, how to determine the voltage change rate will be described in detail. Please refer to... Figure 3 , Figure 3 This is a schematic flowchart of determining the voltage change rate provided in an embodiment of this application. The determination of the voltage change rate in step S20 may include the following steps S201 to S203.

[0060] Step S201: Obtain the initial open-circuit voltage of the battery pack at the end of the discharge to the load device.

[0061] For example, the initial open-circuit voltage of the battery pack at the end of its discharge to the load device can be obtained. For instance, at the end of the battery pack's discharge to the load device, the voltage across the battery pack recorded by the BMS system can be read as the initial open-circuit voltage. This initial open-circuit voltage can be represented as V0.

[0062] It should be noted that when the battery pack is disconnected from the load device, the voltage across the battery pack is equal to the open-circuit voltage.

[0063] Step S202: Obtain the target open-circuit voltage of the battery pack after a preset resting time.

[0064] For example, the target open-circuit voltage of the battery pack after a preset resting time can be obtained.

[0065] For example, when the battery pack has been idle for a preset period of time, the voltage across the battery pack recorded by the BMS system can be read and used as the target open-circuit voltage. The target open-circuit voltage can be represented as V1.

[0066] Step S203: Determine the voltage change rate based on the initial open-circuit voltage, the target open-circuit voltage, and the preset duration.

[0067] In this embodiment of the application, after obtaining the sum of the initial open-circuit voltage and the template open-circuit voltage of the battery pack during the resting process, the voltage change rate can be determined based on the initial open-circuit voltage, the target open-circuit voltage, and the preset time.

[0068] In the above embodiments, by obtaining the initial open-circuit voltage of the battery pack at the end of discharging the load device and the target open-circuit voltage of the battery pack after a preset resting time, the voltage change rate of the battery pack after a preset resting time can be determined based on the initial open-circuit voltage, the target open-circuit voltage, and the preset time.

[0069] Please see Figure 4 , Figure 4 This is a schematic flowchart of a sub-step for determining the rate of change of voltage provided in an embodiment of this application. Determining the rate of change of voltage in step S203 may include the following steps S2031 and S2032.

[0070] Step S2031: Determine the open-circuit voltage difference based on the difference between the target open-circuit voltage and the initial open-circuit voltage.

[0071] For example, the target open-circuit voltage U1 can be subtracted from the initial open-circuit voltage U0 to obtain the open-circuit voltage difference. Wherein, the open-circuit voltage difference ΔU = U1 - U0.

[0072] Step S2032: Calculate the voltage change rate based on the open-circuit voltage difference and the preset time to obtain the voltage change rate.

[0073] In this embodiment of the application, after determining the open-circuit voltage difference, the voltage change rate can be calculated based on the open-circuit voltage difference and a preset time to obtain the voltage change rate.

[0074] For example, the voltage change rate can be obtained by dividing the open-circuit voltage difference by a preset duration. The voltage change rate dv / dt = ΔU / t = (U1 - U0) / t. For instance, when the target open-circuit voltage U1 is 4271mV and the initial open-circuit voltage U0 is 4269mV, if the preset duration t is 10 minutes, the voltage change rate dv / dt = 3.3μV / s can be calculated.

[0075] In the above embodiments, the voltage change rate of the battery pack can be obtained by calculating the voltage change rate based on the open-circuit voltage difference and a preset time.

[0076] Please see Figure 5 , Figure 5 This is a schematic flowchart of a sub-step for predicting the state of charge of a battery pack according to an embodiment of this application. Predicting the state of charge of the battery pack in step S30 may include the following steps S301 to S303.

[0077] Step S301: Based on the preset correspondence between battery temperature and discharge current rate, determine multiple candidate open circuit voltage and state of charge relationship tables corresponding to discharge current rates according to the static temperature value. The voltage change rate range in the candidate open circuit voltage and state of charge relationship tables corresponding to different discharge current rates is different.

[0078] It should be noted that, in this embodiment, a table relating open-circuit voltage to state of charge (SCC) for different battery temperatures and discharge current rates can be pre-constructed, and the different battery temperatures and discharge current rates can be associated and stored with the corresponding open-circuit voltage and SCC tables. For example, when the battery temperature is 5°C, a table relating open-circuit voltage to SCC corresponding to discharge current rates of 0.2C, 0.5C, 1C, and 2C can be constructed. Similarly, when the battery temperature is -5°C, a table relating open-circuit voltage to SCC corresponding to discharge current rates of 0.2C, 0.5C, 1C, and 2C can be constructed. Here, battery temperature refers to the ambient temperature of the battery pack; for example, the battery temperature can be controlled by a heating chamber.

[0079] Please refer to Tables 1 to 4, which are tables showing the relationship between open-circuit voltage and state of charge provided in the embodiments of this application.

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085] Table 3

[0086]

[0087]

[0088] Table 4

[0089]

[0090] As shown in Tables 1 to 4, Table 1 is the relationship between open-circuit voltage and state of charge at a temperature of 5℃ and a discharge current of 0.2C; Table 2 is the relationship between open-circuit voltage and state of charge at a temperature of 5℃ and a discharge current of 1C; Table 3 is the relationship between open-circuit voltage and state of charge at a temperature of -5℃ and a discharge current of 0.2C; and Table 4 is the relationship between open-circuit voltage and state of charge at a temperature of -5℃ and a discharge current of 1C.

[0091] For example, based on a preset correspondence between battery temperature and discharge current rate, multiple candidate open-circuit voltage and state of charge (SCC) tables corresponding to different discharge current rates can be determined according to the resting temperature value. For instance, when the resting temperature is 5°C, candidate open-circuit voltage and SCC tables can be determined as follows: Table 1 for a discharge current rate of 0.2C, Table 2 for a discharge current rate of 1C, and so on. Similarly, when the resting temperature is -5°C, candidate open-circuit voltage and SCC tables can be determined as follows: Table 3 for a discharge current rate of 0.2C, Table 4 for a discharge current rate of 1C, and so on.

[0092] It should be noted that, at the same battery temperature, the range of the rate of change of the candidate open-circuit voltage and the state of charge relationship table are different for different discharge current rates.

[0093] As shown in Tables 1 to 4, at a static temperature of 5°C, the voltage change rate range in the candidate open-circuit voltage and state of charge relationship table corresponding to a discharge current ratio of 0.2C is [5, 8], and the voltage change rate range in the candidate open-circuit voltage and state of charge relationship table corresponding to a discharge current ratio of 1C is [32, 35]. At a temperature of -5°C, the voltage change rate range in the candidate open-circuit voltage and state of charge relationship table corresponding to a discharge current ratio of 0.2C is [2, 3], and the voltage change rate range in the candidate open-circuit voltage and state of charge relationship table corresponding to a discharge current ratio of 1C is [17, 20].

[0094] Step S302: Match the voltage change rate with the voltage change rate interval in each candidate open-circuit voltage and state of charge relationship table, and determine the successfully matched candidate open-circuit voltage and state of charge relationship table as the target open-circuit voltage and state of charge relationship table.

[0095] In this embodiment of the application, after determining multiple candidate open-circuit voltage and state of charge relationship tables corresponding to multiple discharge current ratios based on the static temperature value, the voltage change rate can be matched with the voltage change rate range in each candidate open-circuit voltage and state of charge relationship table, and the successfully matched candidate open-circuit voltage and state of charge relationship table is determined as the target open-circuit voltage and state of charge relationship table.

[0096] For example, when the static temperature is -5℃, the voltage change rate dv / dt = 3.3μv / s in step S2032 can be matched with the voltage change rate range in Tables 3 and 4 of the candidate open-circuit voltage and state of charge relationship. The candidate open-circuit voltage and state of charge relationship table with the smallest voltage change rate error is determined as the target open-circuit voltage and state of charge relationship table. For example, the target open-circuit voltage and state of charge relationship table is Table 3 of the open-circuit voltage and state of charge relationship table.

[0097] By determining candidate open-circuit voltage and state of charge relationship tables corresponding to multiple discharge current ratios based on the static temperature value, the voltage change rate can be matched with the voltage change rate range in each candidate open-circuit voltage and state of charge relationship table, thereby determining the target open-circuit voltage and state of charge relationship table.

[0098] Step S303: Based on the target open-circuit voltage and state of charge relationship table, determine the state of charge of the battery pack according to the target open-circuit voltage.

[0099] For example, after determining the target open-circuit voltage and state of charge relationship table, the state of charge of the battery pack can be determined based on the target open-circuit voltage.

[0100] In some embodiments, determining the state of charge (SOC) of the battery pack based on the target open-circuit voltage and the state of charge (SOC) relationship table may include: determining the open-circuit voltage range to which the target open-circuit voltage belongs, the open-circuit voltage range including a first open-circuit voltage and a second open-circuit voltage; determining the SOC range corresponding to the open-circuit voltage range, the SOC range including a first SOC corresponding to the first open-circuit voltage and a second SOC corresponding to the second open-circuit voltage; and calculating the SOC corresponding to the target open-circuit voltage based on the open-circuit voltage range and the SOC range.

[0101] For example, referring to Table 3 on the relationship between open-circuit voltage and state of charge, for a target open-circuit voltage U1, if the target open-circuit voltage U1 = 4271mV, then the open-circuit voltage range to which the target open-circuit voltage U1 belongs can be determined as (4374mV, 4162mV), where the first open-circuit voltage is 4374mV and the second open-circuit voltage is 4162mV. Furthermore, the state of charge range corresponding to the target open-circuit voltage U1 can be determined as (100%, 90%), where the first open-circuit voltage 4374mV corresponds to a state of charge of 100%, and the second open-circuit voltage 4162mV corresponds to a state of charge of 90%.

[0102] For example, the state of charge corresponding to the target open-circuit voltage can be calculated based on the interpolation formula, according to the open-circuit voltage range and the state of charge range corresponding to the target open-circuit voltage.

[0103] The interpolation calculation formula is as follows:

[0104] SOC=k*OCV+b

[0105] In the formula, k and b represent parameters.

[0106] For example, for the target open-circuit voltage U1, the open-circuit voltage range (4374mV, 4162mV) and the state of charge range (100%, 90%) corresponding to the target open-circuit voltage U1 can be substituted into the above interpolation formula to calculate the values ​​of parameters k and b. Then, substituting the target open-circuit voltage U1 = 4271mV into the above interpolation formula to calculate the state of charge, we can obtain that the state of charge SOC1 corresponding to the target open-circuit voltage U1 is 95%. The specific calculation process is not detailed here.

[0107] In the above embodiments, the state of charge of the battery pack can be accurately and conveniently determined based on the target open-circuit voltage and state of charge relationship table. By using interpolation formulas, the state of charge corresponding to the target open-circuit voltage can be calculated conveniently and accurately, improving the accuracy of determining the battery pack's state of charge.

[0108] In this embodiment, a detailed explanation will be provided on how to construct the open-circuit voltage versus state of charge table for different battery temperatures and discharge current rates. Please refer to [link to relevant documentation]. Figure 6 , Figure 6 This is another schematic flowchart for predicting the state of charge of a battery pack according to an embodiment of this application, which may include the following steps S40 and S50.

[0109] Step S40: Determine multiple preset battery temperatures and multiple discharge current rates corresponding to each battery temperature.

[0110] It should be noted that, in this embodiment of the application, multiple battery temperatures and multiple discharge current rates corresponding to each battery temperature can be set. For example, the battery temperature can be -10℃, -5℃, 0℃, 5℃, 10℃, 20℃, etc., and the discharge current rate corresponding to the battery temperature of -5℃ can be 0.1C, 0.2C, 0.5C, 1C, 2C, etc., and the discharge current rate corresponding to the battery temperature of 5℃ can be 0.1C, 0.2C, 0.5C, 1C, 2C, etc.

[0111] Step S50: Construct a table showing the relationship between open-circuit voltage and state of charge for multiple discharge current rates corresponding to each battery temperature.

[0112] For example, after determining multiple battery temperatures and multiple discharge current rates corresponding to each battery temperature, a table showing the relationship between open-circuit voltage and state of charge for each battery temperature and multiple discharge current rates can be constructed.

[0113] In some embodiments, constructing a table of open-circuit voltage and state of charge (SCC) relationships for multiple discharge current rates corresponding to each battery temperature may include: controlling the battery pack to discharge multiple times according to a preset discharge strategy at each battery temperature, and measuring the SCC, open-circuit voltage, and voltage change rate corresponding to each discharge of the battery pack; generating a table of open-circuit voltage and SCC relationships for different discharge current rates corresponding to each battery temperature based on the SCC, open-circuit voltage, and voltage change rate corresponding to each discharge.

[0114] The discharge strategy includes different discharge current rates and different discharge durations, with the product of the discharge current rate and discharge duration being a preset value. It should be noted that the preset value can be determined based on the battery pack's capacity; for example, 10% of the battery pack's capacity could be used as the preset value. In essence, by setting the product of the discharge current rate and discharge duration as a preset value, the change in the battery pack's state of charge (SOC) during each discharge can be kept constant, for example, a 10% change in SOC after each discharge.

[0115] For example, at a battery temperature of -5°C, the battery pack can be controlled to discharge multiple times according to a preset discharge strategy, and the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge can be measured. Similarly, at a battery temperature of 5°C, the battery pack can be controlled to discharge multiple times according to a preset discharge strategy, and the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge can be measured.

[0116] For example, when the battery temperature is 5°C, the discharge process is as follows:

[0117] With the battery pack fully charged, it was discharged at a 0.1C discharge current rate for 60 minutes, ending the discharge every 60 minutes. The initial open-circuit voltage and the target open-circuit voltage after 10 minutes of rest were recorded at the end of each discharge. The state of charge, open-circuit voltage, and rate of change of voltage were measured for each discharge cycle. The open-circuit voltage includes both the initial open-circuit voltage at the end of the discharge and the target open-circuit voltage after 10 minutes of rest.

[0118] With the battery pack fully charged, it was discharged at a 0.2C discharge current rate for 30 minutes, ending the discharge every 30 minutes. The initial open-circuit voltage and the target open-circuit voltage after 10 minutes of rest were recorded at the end of each discharge. The state of charge, open-circuit voltage, and rate of voltage change were measured for each discharge. This process was repeated with different discharge current rates and durations, and the state of charge, open-circuit voltage, and rate of voltage change were measured for each discharge.

[0119] For example, when the battery temperature is -5°C, the discharge process is as follows:

[0120] With the battery pack fully charged, it was discharged at a 0.1C discharge current rate for 60 minutes, ending the discharge every 60 minutes. The initial open-circuit voltage and the target open-circuit voltage after 10 minutes of rest were recorded at the end of each discharge. The state of charge, open-circuit voltage, and rate of change of voltage were measured for each discharge cycle. The open-circuit voltage includes both the initial open-circuit voltage at the end of the discharge and the target open-circuit voltage after 10 minutes of rest.

[0121] With the battery pack fully charged, it was discharged at a 0.2C discharge current rate for 30 minutes, ending the discharge every 30 minutes. The initial open-circuit voltage and the target open-circuit voltage after 10 minutes of rest were recorded at the end of each discharge. The state of charge, open-circuit voltage, and rate of voltage change were measured for each discharge. This process was repeated with different discharge current rates and durations, and the state of charge, open-circuit voltage, and rate of voltage change were measured for each discharge.

[0122] In this embodiment, after measuring the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge of the battery pack, a table showing the relationship between open-circuit voltage and state of charge for different discharge current ratios corresponding to each battery temperature can be generated based on the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge. The calculation process for the voltage change rate can be found in the detailed description of the above embodiments and will not be repeated here. For example, some of the generated open-circuit voltage and state of charge relationship tables are shown in Tables 1 to 4 above.

[0123] In the above embodiments, by discharging the battery pack at different discharge current rates and different discharge durations at each battery temperature, and generating open-circuit voltage and state of charge relationship tables for different discharge current rates corresponding to each battery temperature based on the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge, it is possible to construct multiple open-circuit voltage and state of charge relationship tables for different battery temperatures.

[0124] In some embodiments, before controlling the battery pack to discharge multiple times according to a preset discharge strategy at each battery temperature, the method may further include: determining the state of charge (SOC) of the battery pack; if the SOC of the battery pack is less than a preset SOC threshold, then charging the battery pack until the SOC of the battery pack is greater than or equal to the SOC threshold.

[0125] For example, the state of charge (SOC) of the battery pack recorded by the BMS system can be obtained. When the SOC of the battery pack is less than a preset SOC threshold, the battery pack is charged until the SOC of the battery pack is greater than or equal to the SOC threshold. The preset SOC threshold can be set according to actual conditions, and the specific value is not limited here.

[0126] It should be noted that by charging the battery pack when its state of charge is less than a preset state of charge threshold until the battery pack's state of charge is greater than or equal to the threshold, it can be ensured that the battery pack's state of charge is a fixed value each time it starts discharging.

[0127] For example, the preset state of charge threshold can be 100%. It can be understood that by charging the battery pack until the state of charge of the battery pack is greater than or equal to 100%, it can be ensured that the open-circuit voltage and voltage change rate corresponding to 100% state of charge can be measured, thereby improving the data integrity of the open-circuit voltage and state of charge relationship table.

[0128] The embodiments of this application also provide a computer-readable storage medium storing a computer program, which includes program instructions. A processor executes the program instructions to implement any of the battery pack state-of-charge prediction methods provided in the embodiments of this application.

[0129] For example, when the program is loaded by the processor, it can perform the following steps:

[0130] Obtain the settling temperature of the battery pack after it has been discharged from the load device for a preset time; determine the voltage change rate of the battery pack during the preset settling time; and predict the state of charge of the battery pack based on the settling temperature and the voltage change rate.

[0131] The computer-readable storage medium can be an internal storage unit of the battery pack in the aforementioned embodiments, such as a hard drive or memory of the battery pack. Alternatively, the computer-readable storage medium can be an external storage device of the battery pack, such as a plug-in hard drive, smart media card (SMC), secure digital card (SD card), flash card, etc., mounted on the battery pack.

[0132] Furthermore, a computer-readable storage medium may primarily include a program storage area and a data storage area, wherein the program storage area may store the operating system, programs required for at least one function, etc.; and the data storage area may store data created according to each program, etc.

[0133] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for predicting the state of charge of a battery pack, characterized in that, Applied to a battery pack, the method includes: Obtain the static temperature value of the battery pack after it has been left to stand for a preset time after discharging the load device; Determine the rate of voltage change of the battery pack during the preset resting time; The state of charge of the battery pack is predicted based on the static temperature value and the voltage change rate. The step of predicting the state of charge (SOC) of the battery pack based on the settling temperature value and the voltage change rate includes: determining multiple candidate open-circuit voltage and SOC relationship tables corresponding to different discharge current ratios based on a preset correspondence between battery temperature and discharge current ratio, wherein the voltage change rate ranges in the candidate open-circuit voltage and SOC relationship tables are different for different discharge current ratios; matching the voltage change rate with the voltage change rate range in each candidate open-circuit voltage and SOC relationship table, and determining the successfully matched candidate open-circuit voltage and SOC relationship table as the target open-circuit voltage and SOC relationship table; and determining the SOC of the battery pack based on the target open-circuit voltage, wherein the target open-circuit voltage is the open-circuit voltage of the battery pack after settling for the preset time.

2. The method for predicting the state of charge of a battery pack according to claim 1, characterized in that, Determining the voltage change rate of the battery pack during the preset resting time includes: Obtain the initial open-circuit voltage of the battery pack at the end of discharging the load device; Obtain the target open-circuit voltage of the battery pack after it has been left to stand for the preset time; The voltage change rate is determined based on the initial open-circuit voltage, the target open-circuit voltage, and the preset duration.

3. The method for predicting the state of charge of a battery pack according to claim 2, characterized in that, Determining the voltage change rate based on the initial open-circuit voltage, the target open-circuit voltage, and the preset duration includes: The open-circuit voltage difference is determined based on the difference between the target open-circuit voltage and the initial open-circuit voltage; The voltage change rate is obtained by calculating the voltage change rate based on the open-circuit voltage difference and the preset time.

4. The method for predicting the state of charge of a battery pack according to claim 1, characterized in that, The target open-circuit voltage and state of charge relationship table includes multiple open-circuit voltages corresponding to different states of charge; the step of determining the state of charge of the battery pack based on the target open-circuit voltage and the target open-circuit voltage relationship table includes: Determine the open-circuit voltage range to which the target open-circuit voltage belongs, wherein the open-circuit voltage range includes a first open-circuit voltage and a second open-circuit voltage; Determine the state of charge interval corresponding to the open circuit voltage interval, wherein the state of charge interval includes a first state of charge corresponding to the first open circuit voltage and a second state of charge corresponding to the second open circuit voltage; The state of charge corresponding to the target open-circuit voltage is calculated based on the open-circuit voltage range and the state of charge range.

5. The method for predicting the state of charge of a battery pack according to claim 1, characterized in that, The method further includes: Determine multiple preset battery temperatures and multiple discharge current rates corresponding to each battery temperature; Construct a table showing the relationship between open-circuit voltage and state of charge for multiple discharge current ratios corresponding to each battery temperature.

6. The method for predicting the state of charge of a battery pack according to claim 5, characterized in that, The construction of the open-circuit voltage and state of charge relationship table for multiple discharge current ratios corresponding to each battery temperature includes: At each battery temperature, the battery pack is controlled to discharge multiple times according to a preset discharge strategy, and the state of charge, open circuit voltage and voltage change rate of the battery pack are measured for each discharge. The discharge strategy includes different discharge current ratios and different discharge durations, and the product of the discharge current ratio and the discharge duration is a preset value. Based on the state of charge, open-circuit voltage, and voltage change rate corresponding to each discharge, a table of open-circuit voltage and state of charge relationship for different discharge current ratios corresponding to each battery temperature is generated.

7. The method for predicting the state of charge of a battery pack according to claim 6, characterized in that, Before controlling the battery pack to discharge multiple times according to a preset discharge strategy at each battery temperature, the method further includes: Determine the state of charge of the battery pack; If the state of charge of the battery pack is less than a preset state of charge threshold, the battery pack is charged until the state of charge of the battery pack is greater than or equal to the state of charge threshold.

8. A battery pack, characterized in that, The battery pack includes a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the method for predicting the state of charge of a battery pack as described in any one of claims 1 to 7 when executing the computer program.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for predicting the state of charge of a battery pack as described in any one of claims 1 to 7.

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