A method for dynamically correcting and displaying the remaining SOC value of a car battery

Abstract

This invention relates to a method for dynamically correcting and displaying the State of Charge (SOC) value of a car battery, belonging to the field of electric vehicle technology. The method includes: recording the actual SOC value when the vehicle is parked and the open-circuit voltage of the battery before starting; determining the initial SOC value based on the parking time from parking to vehicle startup; and correcting the displayed SOC value for each time interval t during vehicle operation based on the initial SOC value. This invention can continuously and dynamically correct the SOC value between the displayed value and the target value during the correction process, avoiding situations where the displayed SOC value jumps directly to the actual value, thus achieving a smoother transition and preventing sudden increases or decreases in SOC.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle technology, and specifically relates to a method for dynamically correcting and displaying the remaining SOC value of a car battery. Background Technology

[0002] Currently, the State of Charge (SOC) displayed in vehicles is dynamically calculated, using algorithms such as ampere-hour integration, battery-model-based EKF, and particle filtering. Battery models require many parameters to identify, have complex algorithms, and are prone to inaccuracies under extreme conditions. In contrast, ampere-hour integration is widely used due to its simple algorithm and high accuracy.

[0003] To facilitate battery management and enhance user experience, online correction of the State of Charge (SOC) is necessary. A common method for obtaining the calibration baseline is the static OCV method, which uses the principle of thermodynamic equilibrium to derive the SOC-OCV curve. The calibration method involves: reading the displayed SOC at the end of vehicle operation; reading the actual SOC after the vehicle has reached a steady state; and then, during vehicle restart, adjusting the SOC using a coefficient K within a specified time t. 表显 Make corrections, where K = (SOC) 表显 -SOC 真实 ) / t.

[0004] The ampere-hour integration method, SOC = SOC0 - ∫i*dt / C0, has two main calculation methods for C0. One method uses C0 as the value under low-power output conditions at room temperature, which is only related to SOH, i.e., C0 = f(SOH). This method is easily affected by temperature, leading to a significant deviation between the calculated and actual SOC values. During SOC calibration, sharp increases or decreases are likely to occur. Furthermore, this calibration method can only be performed when the initial SOC meets the parking calibration conditions, resulting in low efficiency. The second method treats C0 as a variable, related to SOH and temperature T. When SOC is too low and aggressive driving occurs, it is also related to output power, i.e., C0 = f(SOH, T, Power). However, because it directly displays the SOC, user experience may exhibit reverse logic phenomena such as fluctuating battery levels, increased battery during acceleration, and low voltage despite having battery power when the environment changes. In summary, existing methods for correcting the SOC value of a car battery cause the displayed SOC value to suddenly change to the actual value during the correction process, giving users a feeling of abrupt change.

[0005] To solve the above problems, it is necessary to design a method for dynamically correcting and displaying the remaining SOC value of a car battery. Summary of the Invention

[0006] To address the above problems, this invention provides a method for dynamically correcting and displaying the remaining SOC value of a car battery, the method comprising:

[0007] Record the actual SOC value when the vehicle is parked and the open-circuit voltage of the battery before starting from a standstill;

[0008] The initial value of SOC is determined based on the parking time from when the vehicle stops until it starts moving.

[0009] During vehicle operation, the displayed value of SOC is corrected based on the initial value of SOC for each time interval t.

[0010] Preferably, determining the true value of SOC based on parking duration includes the following steps:

[0011] Preset duration threshold;

[0012] If the parking time exceeds the time threshold, the actual SOC value recorded during parking is cleared, and the initial SOC value is calculated based on the battery temperature and battery open-circuit voltage (OCV) values ​​collected by the battery management system (BMS). Otherwise, the actual SOC value recorded during parking is used as the initial SOC value.

[0013] The true SOC value is calculated based on the battery current value within each time interval t and the battery's total capacity C0 at room temperature. The calculation formula is: SOC 真实 =SOC 初始 -∫i*dt / (μ*C0), i∈N, μ is the capacity decay rate.

[0014] Preferably, the step of correcting the displayed value of SOC for each time interval t based on the initial value of SOC includes the following steps:

[0015] Based on the current within time t and the average temperature within time t, the process target value of SOC during vehicle operation is obtained by ampere-hour integration.

[0016] The minimum and maximum correction coefficients are preset, and the correction coefficients are derived by combining the displayed value of the SOC and the process target value;

[0017] The displayed value of SOC is corrected and updated according to the correction coefficient.

[0018] Preferably, deriving the process target value of SOC during vehicle operation based on the actual value of SOC includes the following steps:

[0019] The total battery capacity is calculated based on the average battery temperature over each time interval t.

[0020] The process target value is determined based on the battery current value and the total battery capacity within each time interval t.

[0021] Preferably, the calculation formula for determining the process target value based on the battery current value and the total battery capacity within each time interval t is: SOC 计算 =SOC初始 -∫i*dt / (μ*C), where SOC 计算 denoted as the process target value, μ as the capacity decay rate, and C as the total battery capacity at the current temperature.

[0022] Preferably, the step of combining the displayed value of SOC and the process target value to derive the correction coefficient includes: if the process target value of SOC is greater than the displayed value of SOC during vehicle operation, the correction coefficient shall be the minimum correction value.

[0023] Otherwise, calculate the absolute value of the difference between the stated value of SOC and the process target;

[0024] Furthermore, if the absolute value is less than the maximum correction coefficient, the correction coefficient is the ratio of the absolute value to t; otherwise, the correction coefficient is the maximum correction coefficient.

[0025] Preferably, the correction of the displayed value of SOC for each time interval t includes:

[0026] The SOC value at the end of time t is corrected to the difference between the SOC value at the beginning of time t and the correction factor multiplied by time t.

[0027] Preferably, the step of deriving the initial value of SOC based on the battery temperature and battery open-circuit voltage (OCV) values ​​collected by the battery management system (BMS) includes:

[0028] The initial value of SOC is obtained by looking up the SOC-OCV-T two-dimensional table based on the battery temperature and open-circuit voltage (OCV) values ​​collected by the battery management system (BMS).

[0029] In the SOC-OCV-T two-dimensional table, SOC = [0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1]; T = [-30 -20 -10 0 10 25 35 45 55].

[0030] Preferably, the total battery capacity is calculated based on the average battery temperature over each time interval t.

[0031] Obtain the average temperature for each time interval t, interpolate and look up the CT one-dimensional table to get the total battery capacity C;

[0032] In the CT one-dimensional table, T = [-30 -20 -10 0 10 25 35 45 55].

[0033] Preferably, the range of the correction coefficient is (Kmin, Kmax), where Kmin represents the minimum value of the correction coefficient and Kmax represents the maximum value of the correction coefficient.

[0034] The present invention has the following beneficial effects:

[0035] (1) In this invention, when correcting the SOC value of the car battery balance, the SOC value recorded when the vehicle is parked and the open circuit voltage value of the battery before parking and starting are first recorded. Then, the initial value of SOC is determined based on the parking time. When the vehicle is running, the SOC value displayed in each time period t is corrected based on the process target value of SOC. Through the above operation, the SOC value can be continuously and dynamically corrected between the displayed value and the process target value during the correction process. This can avoid the situation where the SOC value of the car battery balance jumps directly from the displayed value to the actual value, thus achieving a good transition effect and making the correction process smoother without any steep rise or fall.

[0036] (2) In this invention, when correcting the displayed value of SOC, it is necessary to calculate the process target value based on the total capacity of the battery at the current temperature. By comparing the displayed SOC value with the process target value of SOC, the SOC display correction strategy is determined to ensure that the whole process is smoothly corrected. Thus, when the car battery environment changes, there will be no reverse logic phenomena such as power jump, power increase during acceleration, or undervoltage when there is power.

[0037] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart illustrating the method for dynamically correcting and displaying the remaining SOC value of a car battery in an embodiment of the present invention is shown.

[0040] Figure 2 A schematic diagram of the SOC-OCV-T two-dimensional table in an embodiment of the present invention is shown;

[0041] Figure 3 A schematic diagram of a CT one-dimensional table is shown in an embodiment of the present invention;

[0042] Figure 4 A schematic diagram illustrating the steps for correcting the remaining battery capacity in an embodiment of the present invention is shown;

[0043] Figure 5 This diagram illustrates the actual value, displayed value, process target value, and correction coefficient of SOC in each time period in an embodiment of the present invention.

[0044] Figure 6 This diagram illustrates how the actual value, displayed value, and process target value of SOC change over time in an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] like Figure 1 As shown, the present invention provides a method for dynamically correcting and displaying the remaining SOC value of a car battery. The method includes: recording the actual SOC value recorded when the vehicle is parked and the open-circuit voltage of the battery before parking and starting; determining the initial SOC value based on the parking time from parking to vehicle starting; and correcting the displayed SOC value for each time period t based on the initial SOC value when the vehicle is running.

[0047] Determining the initial value of SOC based on parking duration includes the following steps:

[0048] A preset time threshold is set; if the parking time exceeds the threshold, the recorded SOC value during parking is cleared, and the initial SOC value is calculated based on the battery temperature and open-circuit voltage (OCV) collected by the Battery Management System (BMS). Otherwise, the recorded SOC value during parking is used as the initial SOC value. The actual SOC value is calculated based on the battery current value and the total battery capacity (C0) at room temperature for each time interval t. The calculation formula is: SOC 真实 =SOC 初始 -∫i*dt / (μ*C0), i∈N, μ is the capacity decay rate.

[0049] The steps to correct the displayed value of SOC for each time interval t based on the process target value of SOC include:

[0050] Based on the current during time t and the average temperature during time t, the process target value of SOC during vehicle operation is obtained by ampere-hour integration.

[0051] The system presets minimum and maximum correction coefficients, with the unit of correction coefficient being 1 / min. These correction coefficients are then derived by combining the displayed SOC value and the process target value. The displayed SOC value is then updated based on these correction coefficients. This continuous dynamic adjustment of the SOC value between the displayed value and the process target value achieves a linear change, avoiding the jumps in SOC caused by directly correcting the displayed value to the actual value, resulting in a smoother change in SOC value.

[0052] The steps to derive the initial value of the vehicle's SOC during operation from the actual SOC value include:

[0053] The total battery capacity is determined based on the average battery temperature over each time interval t; the target value for the process is calculated based on the battery current value and the total battery capacity over each time interval t.

[0054] The formula for calculating the process target value based on the battery current value and total battery capacity within each time interval t is: SOC 计算 =SOC 初始 -∫i*dt / (μ*C), where SOC 计算 Here, μ is the process target value, C is the capacity decay rate, and C is the total battery capacity at the current temperature. When correcting the displayed SOC value, the process target value needs to be calculated based on the total battery capacity at the current temperature. By comparing the displayed SOC value with the process target value, the SOC display correction strategy is determined to ensure a smooth correction throughout the process. This prevents reverse logic phenomena such as sudden changes in battery level, increased battery level during acceleration, or undervoltage despite having battery capacity when the vehicle battery environment changes.

[0055] The correction factors, derived by combining the stated SOC value and the process target value, include:

[0056] If the target value of SOC process is greater than the displayed value of SOC during vehicle operation, the correction coefficient shall be the minimum correction value Kmin.

[0057] Otherwise, calculate the absolute value of the difference between the displayed value of SOC and the process target;

[0058] Furthermore, if the absolute value is less than the maximum correction coefficient, the correction coefficient is the ratio of the absolute value to t; otherwise, the correction coefficient is the maximum correction coefficient kmax.

[0059] The correction of the displayed SOC value for each time interval t includes:

[0060] The SOC value at the end of time t is corrected to the difference between the SOC value at the beginning of time t and the correction factor multiplied by time t.

[0061] The initial value of SOC is derived from the battery temperature and open-circuit voltage (OCV) collected by the battery management system (BMS).

[0062] The initial value of SOC is obtained by looking up the SOC-OCV-T two-dimensional table based on the battery temperature and open-circuit voltage (OCV) values ​​collected by the battery management system (BMS).

[0063] Among them, such as Figure 2 As shown in the SOC-OCV-T two-dimensional table, SOC = [0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1]; T = [-30 -20 -10 0 10 25 35 45 55]. By querying the corresponding battery temperature and battery open-circuit voltage OCV value, the initial value of the corresponding SOC can be obtained.

[0064] like Figure 3 As shown, the total battery capacity is derived from the average battery temperature over each time interval t, including:

[0065] Obtain the average temperature for each time interval t, interpolate and look up the CT one-dimensional table to get the total battery capacity C;

[0066] In the CT one-dimensional table, T = [-30 -20 -10 0 10 25 35 45 55]. By querying the average temperature value for each time interval t, the total capacity C of the battery at the current temperature can be obtained.

[0067] The range of the correction coefficient is (Kmin, Kmax).

[0068] like Figure 4 As shown, the following details the process of updating the vehicle battery's State of Charge (SOC): Recording the actual SOC value when the vehicle is parked. 真实 The open-circuit voltage (OCV) across the battery before parking and starting is used to determine whether the parking duration (t-stop) is greater than the duration threshold (t). 标准 If t-stop is greater than t 标准 Then clear the actual SOC value recorded at the time of parking. 真实 Based on the current battery temperature T0 and battery open-circuit voltage OCV, the true value of SOC (S0C) is obtained by referring to the SOC-OCV-T two-dimensional table. 初始 Otherwise, the actual SOC value recorded at the time of parking will be used. 真实 SOC as the initial value 初始 The vehicle starts and runs for time t, based on the battery temperature T at the beginning of time t. i-1 and the battery temperature T at the end of time period t. i Calculate the average temperature of the battery, average temperature T = (T i-1-T i Then, based on the average temperature T, look up the CT one-dimensional table to obtain the total battery capacity C during the i-th time period t. i Obtain the process current value i(t) of the battery within time period t, and calculate the process target value SOC for the i-th time period t using the ampere-hour integral formula. 计算i Where i = 1, 2, 3..., initially i = 1, increasing sequentially, SOC 计算i =SOC 计算i-1 -∫i*dt / (μ*C i ), determine SOC 计算i With SOC 表显i The size, if SOC 计算i >SOC 表显i If Ki = Kmin, then let f(i) = S0C. 表显i -SOC 计算i First, determine the product of f(i) and the maximum correction coefficient Kmax with the current time ti. If f(i) < Kmax * ti, then the correction coefficient ki = f(i) / t; otherwise, ki = Kmax. Then update the SOC. 表显i =SCO 表显i-1 -k i *t, then determine whether the vehicle has stopped. If the vehicle has not stopped, let i = i + 1, and then check SOC again. 表显i+1 Update and correct until the vehicle stops. When the vehicle stops, record the actual SOC value. 真实 And the open-circuit voltage OCV at both ends of the battery before parking and starting.

[0069] In the above process, when t=0, SOC 计算0 =SOC 初始 During vehicle operation, SOC 表显1 <SOC 表显i+1 .

[0070] As attached Figure 5 As shown, attached Figure 5 The table shows the actual value, displayed value, process target value, and correction factor value of SOC for each time period in this embodiment. Here, time represents the driving time, real represents the actual value of SOC, calculate represents the process target value, display represents the displayed value of SOC, and Ki-real represents the value of the correction factor.

[0071] As attached Figure 6 As shown, attached Figure 6The figures illustrate the changes in the displayed value, the actual value, and the process target value of SOC during the correction process in this embodiment. In the figures, `real` represents the curve showing the change in the actual value of SOC, `calculate` represents the curve showing the change in the process target value, and `display` represents the curve showing the change in the displayed value of SOC. As can be seen from the figures, the correction method proposed in this application does not exhibit sharp increases or decreases in the value of SOC; instead, it shows a linear change without any jumps, resulting in a smoother correction process and a more comfortable user experience.

[0072] Those skilled in the art should understand that, despite the detailed description of the present invention with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for dynamically correcting and displaying the SOC value of a car battery, characterized in that, The method includes: Record the actual SOC value when the vehicle is parked and the open-circuit voltage of the battery before starting from a standstill; The initial value of SOC is determined based on the parking time from when the vehicle stops until it starts moving. During vehicle operation, the displayed SOC value for each time interval t is corrected based on the initial SOC value, including the following steps: Based on the current during time t and the average temperature during time t, the process target value of SOC during vehicle operation is obtained by ampere-hour integration. The process involves setting maximum and minimum correction coefficients and combining the displayed SOC value and the process target value to derive the correction coefficients. This includes: if the process target SOC value is greater than the displayed SOC value during vehicle operation, the correction coefficient is the minimum correction value; otherwise, the absolute value of the difference between the displayed SOC value and the process target value is calculated. If the absolute value is less than the maximum correction coefficient, the correction coefficient is the ratio of the absolute value to t; otherwise, the correction coefficient is the maximum correction coefficient. The process target value of SOC during vehicle operation is derived from the actual SOC value through the following steps: The total battery capacity is calculated based on the average battery temperature over each time interval t; the process target value is calculated based on the battery current value and the total battery capacity over each time interval t, using the following formula: SOC... 计算 =SOC 初始 -∫i dt / ( C), where SOC 计算 For the process target value, Here, C represents the capacity decay rate, and C represents the total battery capacity at the current temperature. The displayed value of SOC is corrected and updated according to the correction coefficient.

2. The method for dynamically correcting and displaying the SOC value of a car battery according to claim 1, characterized in that, The process of determining the initial value of SOC based on parking duration includes the following steps: Preset duration threshold; If the parking time exceeds the time threshold, the actual SOC value recorded during parking is cleared, and the initial SOC value is calculated based on the battery temperature and battery open-circuit voltage (OCV) values ​​collected by the battery management system (BMS). Otherwise, the actual SOC value recorded during parking is used as the initial SOC value. The true SOC value is calculated based on the battery current value within each time interval t and the battery's total capacity C0 at room temperature. The calculation formula is: SOC 真实 =SOC 初始 -∫i dt / ( C0), This represents the capacity decay rate.

3. The method for dynamically correcting and displaying the remaining SOC value of a car battery according to claim 1, characterized in that, The correction of the displayed SOC value for each time interval t includes: The SOC value at the end of time t is corrected to the difference between the SOC value at the beginning of time t and the correction factor multiplied by time t.

4. The method for dynamically correcting and displaying the remaining SOC value of a car battery according to claim 2, characterized in that, The process of deriving the initial value of SOC based on the battery temperature and battery open-circuit voltage (OCV) values ​​collected by the battery management system (BMS) includes: The initial value of SOC is obtained by looking up the SOC-OCV-T two-dimensional table based on the battery temperature and open-circuit voltage (OCV) values ​​collected by the battery management system (BMS). In the SOC-OCV-T two-dimensional table, SOC = [0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1]; T = [-30 -20 -10 0 10 25 35 45 55].

5. The method for dynamically correcting and displaying the remaining SOC value of a car battery according to claim 1, characterized in that, The calculation of the total battery capacity based on the average battery temperature over each time interval t includes: Obtain the average temperature for each time interval t, interpolate and look up the CT one-dimensional table to get the total battery capacity C; In the CT one-dimensional table, T = [-30 -20 -10 0 10 25 35 45 55].

6. The method for dynamically correcting and displaying the SOC value of a car battery according to claim 1, characterized in that, The range of the correction coefficient is (Kmin, Kmax), where Kmin represents the minimum value of the correction coefficient and Kmax represents the maximum value of the correction coefficient.

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