Battery charge state smoothing display method, device, and storage medium

Abstract

The application relates to the field of BMS management, and discloses a battery state-of-charge smoothing display method, equipment and a storage medium. The method comprises the following steps: collecting the current temperature, current and terminal voltage of the battery to obtain an initial state-of-charge; querying the direct-current internal resistance in a preset internal resistance mapping relationship according to the current temperature and the charging and discharging rate determined by the current, and performing voltage drop compensation on the terminal voltage according to the direct-current internal resistance and the current to obtain a compensated voltage; when the compensated voltage reaches a terminal voltage threshold value, determining a correction rate according to the state-of-charge difference between the real state-of-charge and the initial state-of-charge; and performing weighted ampere-hour integral operation on the current by taking the correction rate as an integral gain to obtain and output a smoothed display state-of-charge. In the embodiment of the application, the influence of temperature change and voltage characteristic change at the capacity pole on the state-of-charge display can be reduced, and the state-of-charge can be prevented from suddenly changing at high and low temperatures and at the capacity pole.

Description

Technical Field

[0001] This invention relates to the field of BMS management, and more particularly to a method, device, and storage medium for smooth display of battery state of charge. Background Technology

[0002] The state of charge (SOC) of a battery refers to the ratio of its current remaining capacity to its nominal capacity. It is usually expressed as a percentage and is a core indicator reflecting the real-time remaining capacity of a battery.

[0003] Currently, traditional SOC estimation methods are based on the ampere-hour integration method, supplemented by the OCV correction method. However, this method does not consider that the actual usable capacity of the battery cell will significantly decrease compared to the rated capacity at different charge / discharge rates and temperatures. This causes the SOC to jump to 100% or 0% before it is fully charged or discharged, resulting in abrupt changes in the displayed value. Furthermore, under high-rate and high-temperature conditions, the cell-end voltage will experience drastic rises or falls due to ohmic and polarization internal resistances. Traditional methods, which rely solely on the terminal voltage to determine full charge or discharge, are prone to false triggering, causing SOC values ​​to jump. The traditional ampere-hour integration method is also highly susceptible to severe SOC fluctuations at the end due to integration errors or voltage sampling noise, seriously affecting user experience and system reliability.

[0004] Therefore, a technology is needed to address the technical problem that the state of charge of batteries in existing technologies will change abruptly under high and low temperature conditions and at capacity extremes. Summary of the Invention

[0005] The main objective of this invention is to solve the technical problem that the state of charge of batteries in the prior art will change abruptly under high and low temperature conditions and at capacity extremes.

[0006] The first aspect of the present invention provides a method for smoothly displaying the state of charge of a battery, the method comprising: Collect the current temperature, current current and terminal voltage of the battery, and perform ampere-hour integration on the current current based on the preset available capacity to obtain the initial state of charge; Based on the current temperature and the charge / discharge rate determined by the current current, the DC internal resistance is retrieved from the preset internal resistance mapping relationship, and the voltage drop compensation is performed on the terminal voltage based on the DC internal resistance and the current current to obtain a compensation voltage that characterizes the true internal voltage of the battery. The compensation voltage is compared with a preset end voltage threshold; when the compensation voltage reaches the end voltage threshold, a correction rate matching the state of charge difference is determined based on the state of charge difference between the actual state of charge corresponding to the end voltage threshold and the initial state of charge. Using the correction rate as the integral gain, a weighted ampere-hour integral is performed on the current to correct the initial state of charge to the true state of charge, and the state of charge is obtained and output as a smooth display.

[0007] Optionally, in a first implementation of the first aspect of the present invention, before the step of querying the DC internal resistance from a preset internal resistance mapping relationship based on the current temperature and the charge / discharge rate determined by the current current, the method includes: Under various temperature and rate combinations consisting of multiple preset temperature points and multiple preset rate points, a pulse current is applied to the battery in a stable voltage state, and the voltage change caused by the pulse current is collected. Based on a preset internal resistance calculation formula, the DC internal resistance is calculated using the voltage change and the pulse current, wherein the internal resistance calculation formula includes:

[0008] Among them, C r R0(T, C) represents the charge / discharge rate, T represents the temperature, and R0(T, C) represents the charge / discharge rate. r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding DC internal resistance, ΔV is the voltage change caused by the pulse current, I p The amplitude of the pulse current; Based on the mapping relationship between all temperature ratio combinations and DC internal resistance, an internal resistance mapping relationship is constructed.

[0009] Optionally, in a second implementation of the first aspect of the present invention, the step of using the correction rate as the integral gain to perform a weighted ampere-hour integral operation on the current current to correct the initial state of charge to the true state of charge, and obtaining and outputting a smoothly displayed state of charge includes:

[0010] Among them, SOC d (t) represents the smoothed displayed state of charge at time t, SOC0 represents the initial state of charge at the start of the end correction, J represents the correction rate, I(τ) represents the charging and discharging current at time τ, taking a positive value during discharging and a negative value during charging, and C a t represents the available capacity, and t represents the cumulative duration since the start of the end correction.

[0011] Optionally, in a third implementation of the first aspect of the present invention, the step of performing voltage drop compensation on the terminal voltage based on the DC internal resistance and the current current to obtain a compensation voltage characterizing the true internal voltage of the battery includes: V 内 =V 端 +R0*I Among them, V 内 The compensation voltage, V, is used to characterize the actual internal voltage of the battery. 端 R0 is the terminal voltage, I is the DC internal resistance, and I is the current.

[0012] Optionally, in a fourth implementation of the first aspect of the present invention, the step of determining a correction rate matching the state of charge difference based on the state of charge difference between the actual state of charge corresponding to the terminal voltage threshold and the initial state of charge includes: The absolute value of the state of charge difference is matched with several preset continuous numerical intervals to obtain a correction rate that matches the state of charge difference. Each numerical interval corresponds to a different correction rate, and the larger the value of the numerical interval, the larger the corresponding correction rate.

[0013] Optionally, in a fifth implementation of the first aspect of the present invention, after the step of performing a weighted ampere-hour integral operation on the current current using the correction rate as the integral gain to correct the initial state of charge to the true state of charge, and obtaining and outputting a smoothly displayed state of charge, the method further includes: In response to the completion of a complete charge-discharge cycle, the measured capacity corresponding to the complete charge-discharge cycle is collected. Based on the measured capacity and the capacity loss coefficient associated with the current temperature and the charge-discharge rate, the available capacity is updated to obtain the updated available capacity. The updated available capacity is then used as the reference capacity for the next ampere-hour integration calculation.

[0014] Optionally, in a sixth implementation of the first aspect of the present invention, the step of collecting the measured capacity corresponding to the complete charge-discharge cycle includes: The charging and discharging current is integrated over the entire charging and discharging cycle from full charge to vent or from vent to full charge to obtain the measured capacity corresponding to the complete charging and discharging cycle.

[0015] Optionally, in a seventh implementation of the first aspect of the present invention, the step of updating the available capacity based on the measured capacity and the capacity loss coefficient associated with the current temperature and the charge / discharge rate to obtain the updated available capacity includes:

[0016] Among them, C a For available capacity, C m For the measured capacity, K(T, C) r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding capacity loss factor and K(T, C) r )≤1, T is the current temperature, and Cr is the charge / discharge rate.

[0017] A second aspect of the present invention provides a battery state of charge smoothing display device, comprising: a memory and at least one processor, wherein the memory stores instructions, and the memory and the at least one processor are interconnected via a circuit; the at least one processor invokes the instructions in the memory to cause the battery state of charge smoothing display device to perform the above-described battery state of charge smoothing display method.

[0018] A third aspect of the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described method for smoothing the display of battery state of charge.

[0019] In this embodiment of the invention, the current temperature, current, and terminal voltage of the battery are collected. Combined with the DC internal resistance corresponding to the temperature and charge / discharge rate, the terminal voltage is compensated for voltage drop, enabling the compensated voltage to represent the true internal voltage of the battery. When the compensated voltage reaches a preset terminal voltage threshold, a corresponding correction rate is matched based on the difference between the true state of charge (SOC) corresponding to this threshold and the initial SOC obtained by ampere-hour integration. This correction rate is then used as the integration gain for weighted ampere-hour integration, gradually correcting the initial SOC to the true SOC. This reduces the impact of temperature changes and voltage characteristic changes at capacity limits on the displayed SOC, preventing abrupt changes in SOC at high and low temperatures and at capacity limits, achieving a smooth display of the battery's SOC, and solving the technical problem of jumps in battery charge state at high and low temperatures and at capacity limits in existing technologies. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an embodiment of the battery state of charge smoothing display method in this invention; Figure 2 This is a schematic diagram of a specific embodiment preceding step 102 of the battery state of charge smoothing display method in this invention. Figure 3 This is a schematic diagram of another specific embodiment of the battery state of charge smoothing display method in this invention; Figure 4 This is a schematic diagram of one embodiment of the battery state of charge smoothing display device according to the present invention. Detailed Implementation

[0021] This invention provides a method, device, and storage medium for smoothly displaying the state of charge of a battery.

[0022] The embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0023] In the description of the embodiments disclosed in this invention, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0024] For ease of understanding, the specific process of the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 1 One embodiment of the battery state of charge smoothing display method in this invention includes: 101. Collect the current temperature, current current and terminal voltage of the battery, and perform ampere-hour integration on the current current based on the preset available capacity to obtain the initial state of charge; In this embodiment, the battery management system acquires the current temperature T through a temperature sensor, the current I through a current sensor, and the battery terminal voltage V through a voltage sampling circuit. 端 The current carries information about the charging and discharging direction. The battery management system also determines the current charge / discharge rate C based on the ratio between the absolute value of the current current and the capacity reference. r :

[0025] Where Cr is the current charge / discharge rate, in C; I is the current charge / discharge current, in A, taking a positive value during discharge and a negative value during charging; |I| is the absolute value of the current charge / discharge current; C ref This is the capacity reference used to calculate the charge / discharge rate, in Ah. During the initial system startup, C... ref The rated capacity of the battery is used; after the system obtains the measured capacity corresponding to a complete charge-discharge cycle, the capacity updated based on the measured capacity is used as the capacity benchmark.

[0026] After acquiring the current current, the battery management system uses the current available capacity C. a To calculate the initial state of charge (SOC) based on the baseline capacity of the ampere-hour integral, we take the example of the discharge current decreasing the SOC and the charging current increasing the SOC. The continuous integral form is as follows:

[0027] Among them, SOC i (t) represents the initial state of charge at time t, in %; SOC i (t0) represents the state of charge at the start time t0 of the integration, in %; t0 is the start time of this ampere-hour integration, in seconds; t is the current time, in seconds; τ is the time variable during the integration process, in seconds; I(τ) is the charging and discharging current at time τ, in A, taking a positive value during discharging and a negative value during charging; C a The current available capacity is expressed in Ah; 3600 is the conversion factor between seconds and hours; 100 is used to convert the state of charge to a percentage.

[0028] Since I is positive during discharge, the above integral result causes the initial state of charge to gradually decrease; during charging, I is negative, and the negative sign before the integral term causes the initial state of charge to gradually increase. Therefore, this formula is consistent with the current direction specified in this embodiment.

[0029] In the battery management system, the above ampere-hour integral is calculated discretely according to the sampling period:

[0030] Among them, SOC i (k) represents the initial state of charge calculated at the k-th sampling time, in %; SOC i (k-1) represents the initial state of charge at the (k-1)th sampling time, in %; k is the sampling number corresponding to the current sampling time; I(k) is the charging and discharging current collected at the kth sampling time, in A; Δt is the sampling period between the (k-1)th and kth sampling times, in s; C a The current available capacity is expressed in Ah; 3600 is the conversion factor between seconds and hours; 100 is the percentage conversion factor.

[0031] The available capacity used in this embodiment is not always fixed to the battery's factory rated capacity, but is determined based on the measured capacity corresponding to a complete charge-discharge cycle, as well as the capacity loss factor corresponding to the current temperature and current charge-discharge rate. Therefore, under conditions of low temperature, high rate, or battery aging, the capacity used for ampere-hour integration can be adapted to the battery's current actual release capacity.

[0032] 102. Based on the current temperature and the charge / discharge rate determined by the current current, the DC internal resistance is retrieved from the preset internal resistance mapping relationship, and the voltage drop compensation is performed on the terminal voltage based on the DC internal resistance and the current current to obtain a compensation voltage that characterizes the true internal voltage of the battery. In this embodiment, under low temperature or high-rate charge / discharge conditions, the battery terminal voltage is significantly affected by the internal resistance voltage drop. For example, during high-rate discharge, even if the battery has not reached a fully discharged state, the terminal voltage may drop prematurely to near the discharge end voltage due to the internal resistance voltage drop. If the terminal voltage is directly used to determine whether the battery has reached the discharge end, it is easy to falsely trigger SOC zeroing. Correspondingly, during high-rate charging, the terminal voltage may rise prematurely to near the charging end voltage due to the internal resistance voltage drop, thereby falsely triggering SOC full charge calibration.

[0033] To mitigate the aforementioned impacts, this embodiment pre-calibrates the DC internal resistance at different temperatures and charge / discharge rates, and stores the calibration results in the battery management system.

[0034] When establishing the internal resistance mapping relationship, the battery under test was adjusted to a stable voltage state and placed in temperature environments of -40℃, -20℃, 0℃, 25℃, 45℃, 60℃, and 65℃, respectively. Once the battery temperature reached the corresponding temperature point and remained stable, pulse currents of 0.5C, 1C, 2C, and 5C were applied to the battery, respectively. The duration of the pulse current was set to 10 seconds, and the voltage changes caused by the pulse current were collected.

[0035] The DC internal resistance corresponding to temperature T and charge / discharge rate Cr is calculated according to the following formula:

[0036] Where R0(T,Cr) is the DC internal resistance corresponding to temperature T and charge / discharge rate Cr, in Ω; T is the battery temperature during pulse testing, in °C; Cr is the charge / discharge rate during pulse testing, in C; ΔV is the voltage change before and after applying the pulse current, in V; |ΔV| is the absolute value of the voltage change; I p The pulse current applied to the battery, measured in amperes (A); |I p | represents the absolute value of the pulse current. Specifically, in step 102, "based on the DC internal resistance and the current current, the terminal voltage is compensated for voltage drop to obtain a compensation voltage characterizing the true internal voltage of the battery," which includes the following specific implementation methods: V 内 =V 端 +R0*I , where V 内 The compensation voltage, V, is used to characterize the actual internal voltage of the battery. 端 R0 is the terminal voltage, I is the DC internal resistance, and I is the current.

[0037] In this embodiment, during discharge, I is positive, and the battery terminal voltage is lower than the internal battery voltage due to the internal resistance voltage drop. Therefore, R0I is added to the terminal voltage to obtain a compensation voltage. During charging, I is negative, R0I is negative, and the compensation voltage is lower than the measured terminal voltage, thereby eliminating the voltage rise caused by the internal resistance voltage drop during charging.

[0038] For example, if the battery is operating at 25℃ and 2C discharge conditions, the DC internal resistance is found to be 2.3mΩ according to Table 1. The current discharge current is 200A, and the measured terminal voltage is 3.10V. Therefore, the compensation voltage is V. 内 =3.10+0.0023*200=3.56V, where 3.10 is the collected terminal voltage value in V; 0.0023 is the DC internal resistance value after converting 2.3mΩ to Ω; 200 is the current discharge current value in A; and 3.56 is the calculated compensation voltage value in V.

[0039] As can be seen from the above calculations, if the terminal voltage of 3.10V is used directly for end-of-discharge judgment, it may be mistakenly believed that the battery is close to the end of discharge. The 3.56V obtained after DC internal resistance compensation can more accurately reflect the current internal voltage of the battery, thus reducing the end-of-discharge misjudgment caused by low temperature and high rate conditions.

[0040] For further details, please refer to Figure 2 , Figure 2 This is a schematic diagram of a specific embodiment prior to step 102 of the battery state of charge smoothing display method in this invention. The following specific implementation methods are also included before step 102: 1021. Under various temperature and rate combinations consisting of multiple preset temperature points and multiple preset rate points, a pulse current is applied to the battery in a stable voltage state, and the voltage change caused by the pulse current is collected. 1022. Based on the preset internal resistance calculation formula, the DC internal resistance is calculated using the voltage change and the pulse current, wherein the internal resistance calculation formula includes:

[0041] Among them, C r R0(T, C) represents the charge / discharge rate, T represents the temperature, and R0(T, C) represents the charge / discharge rate. r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding DC internal resistance, ΔV is the voltage change caused by the pulse current, I p The amplitude of the pulse current; 1023. Based on the mapping relationship between all temperature ratio combinations and DC internal resistance, an internal resistance mapping relationship is constructed.

[0042] In steps 1021-1023, the internal resistance calibration can employ the Hybrid Pulse Power Characteristic (HPPC) test method. Specifically, multiple preset temperature points may include, for example, -40℃, -20℃, 0℃, 25℃, 45℃, 60℃, and 65℃, and multiple preset rate points may include, for example, 0.5C, 1C, 2C, and 5C. Under each temperature and rate combination, the battery is first placed in the corresponding temperature environment and allowed to settle sufficiently to achieve a stable voltage state, such as placing the lithium iron phosphate battery in a plateau voltage range near 3.2V. Then, a pulse current is applied to the battery for a continuous preset duration, for example, 10s. The voltage change caused by the sudden current change is collected, and the DC internal resistance under that temperature and rate combination is calculated according to the aforementioned internal resistance calculation formula. After traversing all temperature and rate combination conditions, a three-dimensional mapping relationship between temperature, rate, and DC internal resistance can be constructed and pre-stored in the battery management system's memory for querying and recall during real-time operation.

[0043] Multiple pulse tests were performed under each temperature ratio combination, and the average value of the multiple test results was used as the DC internal resistance corresponding to that temperature ratio combination. After completing all the tests, the internal resistance mapping table shown in Table 1 was obtained.

[0044] Table 1. Internal Resistance Mapping Table (Unit: mΩ) temperature 0.5C internal resistance 1C internal resistance 2C internal resistance 5C internal resistance -40℃ 12.5 13.8 15.6 19.5 -20℃ 8.5 9.2 10.1 12.3 0℃ 4.2 4.5 5.0 6.1 25℃ 2.0 2.1 2.3 2.8 45℃ 1.8 1.9 2.0 2.4 60℃ 1.7 1.8 1.9 2.2 65℃ 1.6 1.7 1.8 2.1 The values ​​in Table 1 illustrate the specific form of the internal resistance mapping relationship. In practical applications, the DC internal resistance corresponding to each temperature rate combination is determined based on the battery's material system, capacity, model, and calibration results.

[0045] During battery operation, the battery management system looks up the DC internal resistance in the internal resistance mapping relationship shown in Table 1 based on the current temperature T and current charge / discharge rate Cr obtained in step 101. For example, when the current temperature is 25°C and the current charge / discharge rate is 2C, the retrieved DC internal resistance is 2.3mΩ. When the current temperature or current charge / discharge rate is between two adjacent calibration points, linear interpolation is performed based on the DC internal resistance corresponding to the adjacent calibration points to obtain the DC internal resistance that matches the current operating condition.

[0046] 103. Compare the compensation voltage with a preset end voltage threshold; when the compensation voltage reaches the end voltage threshold, determine a correction rate that matches the state of charge difference based on the state of charge difference between the actual state of charge corresponding to the end voltage threshold and the initial state of charge. In this embodiment, charging end voltage threshold and discharging end voltage threshold are set for lithium iron phosphate batteries. The charging end voltage threshold is 3.65V, which corresponds to a true state of charge of 100%; the discharging end voltage threshold is 2.8V, which corresponds to a true state of charge of 0%.

[0047] During battery charging, the battery management system compares the compensation voltage obtained in step 102 with 3.65V. When the compensation voltage is greater than or equal to 3.65V and this condition is met for 1 second, the battery is determined to have reached the end of charging. During battery discharging, the battery management system compares the compensation voltage with 2.8V. When the compensation voltage is less than or equal to 2.8V and this condition is met for 1 second, the battery is determined to have reached the end of discharging. By setting a 1-second continuous confirmation time, single voltage sampling noise or instantaneous current changes can avoid false triggering of end-of-charge correction.

[0048] After confirming that the compensation voltage has reached the end voltage threshold, the battery management system reads the current initial state of charge and calculates the state of charge difference between the actual state of charge corresponding to the end voltage threshold and the initial state of charge:

[0049] Where ΔSOC is the difference in state of charge, in %; SOC target This represents the actual state of charge (SOC) corresponding to the current end-of-charge voltage threshold, expressed as a percentage (%). It is set to 100% when the charging end-of-charge voltage threshold is reached and 0% when the discharging end-of-charge voltage threshold is reached. i To compensate for the voltage reaching the terminal voltage threshold, the initial state of charge is obtained from the ampere-hour integration calculation in step 101, in units of .

[0050] Specifically, in step 103, "determining a correction rate that matches the state of charge difference based on the state of charge difference between the actual state of charge corresponding to the terminal voltage threshold and the initial state of charge" includes the following specific implementation methods: 1031. Match the absolute value of the state of charge difference with a number of preset continuous numerical intervals to obtain a correction rate that matches the state of charge difference, wherein each numerical interval corresponds to a different correction rate, and the larger the value of the numerical interval, the larger the corresponding correction rate.

[0051] In step 1031, the absolute value of the state of charge difference can be divided into three continuous numerical intervals for graded matching: when the absolute value of the state of charge difference is greater than or equal to 10%, the correction rate is 10; when the absolute value of the state of charge difference is greater than or equal to 5% and less than 10%, the correction rate is 5; and when the absolute value of the state of charge difference is less than 5%, the correction rate is 2. In this embodiment, the state of charge difference is divided into three continuous intervals, and the correction rate corresponding to each interval is shown in Table 2.

[0052] Table 2. Correspondence between state of charge difference and correction rate Difference ΔSOC range Correction rate J ≥10% 10 5%~10% 5 <5% 2 In Table 2, |ΔSOC| represents the absolute value of the state of charge difference ΔSOC, expressed as %; J is the correction rate applied to the end-ampere-hour integral change, also known as the integral gain, and is a dimensionless value. A larger state of charge difference corresponds to a larger correction rate; a smaller state of charge difference corresponds to a smaller correction rate. Through graded adjustment, the displayed state of charge eventually converges to the true value while avoiding steep jumps in the curve. In other alternative implementations, the numerical interval can be divided into 4 or 5 levels, and the correction rate corresponding to each level can be set according to actual calibration requirements. Gradient-graded pursuit can also be achieved using smoothing algorithms such as linear interpolation, exponential smoothing, or proportional-integral-derivative (PID) regulation, as long as the displayed state of charge smoothly approximates the true state of charge rather than abruptly changing.

[0053] 104. Using the correction rate as the integral gain, perform a weighted ampere-hour integral operation on the current current to correct the initial state of charge to the true state of charge, and obtain and output a smooth display of the state of charge.

[0054] In this embodiment, when the compensation voltage has not yet reached the charging end voltage threshold or the discharging end voltage threshold, the battery management system outputs the initial state of charge obtained in step 101 as a smoothed display state of charge. After confirming that the compensation voltage has reached the corresponding end voltage threshold, the battery management system records the initial state of charge when entering the end correction state, and uses the correction rate determined in step 103 as the integration gain to perform weighted ampere-hour integration on the current. When the correction rate is greater than 1, the change in state of charge caused by a unit current is amplified accordingly, and the displayed state of charge catches up with the true state of charge at a rate higher than that of conventional ampere-hour integration; as the displayed state of charge gradually approaches the true state of charge, the difference in state of charge falls into a smaller value range, the correction rate decreases step by step, and the catching-up rate slows down until the displayed state of charge smoothly converges to the true state of charge; after convergence, the correction rate is restored to 1, that is, conventional ampere-hour integration calculation is resumed.

[0055] After entering the end-of-cycle correction state, the battery management system recalculates the difference between the current smoothed displayed state of charge and the actual state of charge in each sampling cycle, and updates the correction rate according to Table 2. When the difference is large, a larger correction rate is used for weighted ampere-hour integration; when the difference decreases, the correction rate is gradually reduced.

[0056] At the end of charging, since the charging current is negative, the weighted ampere-hour integral causes the displayed state of charge to gradually increase. When the displayed state of charge reaches 100%, the output value is limited to 100%, and further upward correction stops. At the end of discharging, since the discharging current is positive, the weighted ampere-hour integral causes the displayed state of charge to gradually decrease. When the displayed state of charge reaches 0%, the output value is limited to 0%, and further downward correction stops.

[0057] Specifically, step 104 includes the following specific implementation methods:

[0058] Among them, SOC d (t) represents the smoothed displayed state of charge at time t, SOC0 represents the initial state of charge at the start of the end correction, J represents the correction rate, I(τ) represents the charging and discharging current at time τ, taking a positive value during discharging and a negative value during charging, and C a t represents the available capacity, and t represents the cumulative duration since the start of the end correction.

[0059] In this embodiment, throughout the entire state of charge (0%~100%) range, the final smoothly displayed state of charge output uses ampere-hour integration as the main path, terminal gradient catching as feedback correction, and internal resistance compensation and capacity correction as feedforward compensation. The consumption time of each state of charge segment varies uniformly with a constant current, without any abrupt changes or non-physical abrupt shifts. The output frequency of the smoothly displayed state of charge is consistent with the sampling period of the battery management system, typically 10Hz~100Hz, to ensure real-time output.

[0060] For further details, please refer to Figure 3 , Figure 3 This is a schematic diagram of another specific embodiment of the battery state of charge smoothing display method in this invention. After step 104, the following specific implementation method is also included: 105. In response to the completion of a complete charge-discharge cycle, the measured capacity corresponding to the complete charge-discharge cycle is collected. Based on the measured capacity and the capacity loss coefficient associated with the current temperature and the charge-discharge rate, the available capacity is updated to obtain the updated available capacity. The updated available capacity is then used as the reference capacity for the next ampere-hour integration calculation.

[0061] In step 105, after the battery completes a full discharge cycle from a fully charged state to a fully discharged state, or a full charge cycle from a discharged state to a fully charged state, the battery management system integrates the current collected during that full charge-discharge cycle to obtain the measured capacity. The measured capacity is calculated according to the following formula:

[0062] Among them, C m The measured capacity corresponding to this complete charge-discharge cycle, in Ah; t s The start time of a complete charge-discharge cycle, measured in seconds (s); t e The end time of a complete charge-discharge cycle is in seconds; t is the time variable during the integration process, in seconds; I(t) is the charging and discharging current at time t within the complete charge-discharge cycle, in A, taking a positive value during discharge and a negative value during charging; 3600 is the conversion factor between seconds and hours; the absolute value symbol is used to uniformly convert the integration result of a complete charging cycle or a complete discharging cycle into a positive capacity value.

[0063] In the battery management system, the measured capacity is calculated discretely according to the following formula:

[0064] Among them, C m The measured capacity corresponding to a complete charge-discharge cycle is expressed in Ah; s is the starting sampling number of the complete charge-discharge cycle; e is the ending sampling number of the complete charge-discharge cycle; k is any sampling number between the starting sampling number s and the ending sampling number e; I(k) is the charge-discharge current at the kth sampling time, expressed in A; Δt is the sampling period, expressed in s; 3600 is the conversion factor between seconds and hours.

[0065] The measured capacity corresponding to the complete charge-discharge cycle is collected, and the available capacity is updated by combining the capacity loss coefficient associated with the current temperature and charge-discharge rate. The updated available capacity is assigned as the reference capacity for the next ampere-hour integration calculation, so that the capacity reference of ampere-hour integration can synchronously track the aging state of the battery throughout its entire life cycle and the capacity loss under low temperature and high rate conditions, thereby eliminating the cumulative drift of ampere-hour integration from the root.

[0066] Furthermore, step 105, "collecting the measured capacity corresponding to the complete charge-discharge cycle," includes the following specific implementation methods: 1051. Integrate the charging and discharging current throughout the entire charging and discharging cycle from fully charged state to discharged state or from discharged state to fully charged state to obtain the measured capacity corresponding to the complete charging and discharging cycle.

[0067] In step 1051, the fully charged state and the discharged state can be determined by reaching the full charge threshold and the discharge threshold, respectively, through compensation voltage. When it is detected that the battery has continuously discharged from the fully charged state to the discharged state, or continuously charged from the discharged state to the fully charged state, a complete charge-discharge cycle is determined to be completed. The charge-discharge current within the complete charge-discharge cycle is integrated over the entire process, and the resulting amount of electricity is the measured capacity corresponding to the complete charge-discharge cycle. After each complete charge-discharge cycle, the latest acquired measured capacity is used to update the available capacity, thereby ensuring the timeliness of the capacity benchmark.

[0068] Furthermore, step 105, "updating the available capacity based on the measured capacity and the capacity loss coefficient associated with the current temperature and the charge / discharge rate to obtain the updated available capacity," includes the following specific implementation methods:

[0069] Among them, C a For available capacity, C m For the measured capacity, K(T, C) r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding capacity loss factor and K(T, C) r )≤1, T is the current temperature, and Cr is the charge / discharge rate.

[0070] In this embodiment, the measured capacity reflects the capacity decay caused by battery cycle aging and calendar aging. After obtaining the measured capacity, the battery management system uses this measured capacity as the basis for subsequent capacity correction and queries the capacity loss factor based on the current temperature and the current charge / discharge rate.

[0071] The capacity loss factor was obtained through a pre-conducted full charge-discharge test. The actual capacity that the battery could release was measured at different temperatures and different charge-discharge rates, and the ratio of this capacity to the reference capacity was calculated, thus forming the temperature, rate, and capacity loss factor mapping table shown in Table 3.

[0072] Table 3. Mapping Table of Temperature, Ratio, and Capacity Loss Coefficient Temperature / Magnification 0.5C 1C 2C 5C -40℃ 0.55 0.50 0.44 0.35 -20℃ 0.75 0.70 0.64 0.55 0℃ 0.92 0.90 0.86 0.80 25℃ 0.99 0.98 0.96 0.92 45℃ 0.98 0.97 0.95 0.91 60℃ 0.97 0.96 0.94 0.90 65℃ 0.96 0.95 0.93 0.89 The values ​​in Table 3 illustrate the specific form of the capacity loss factor mapping relationship. In practical applications, the capacity loss factor corresponding to each temperature rate combination is determined based on the specific cell model and capacity test results.

[0073] The battery management system looks up the corresponding capacity loss factor in Table 3 based on the current temperature T and the current charge / discharge rate Cr, and calculates the current usable capacity according to the following formula:

[0074] Among them, C a For available capacity, C m For the measured capacity, K(T, C) r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding capacity loss factor and K(T, C) r )≤1, T is the current temperature, and Cr is the charge / discharge rate.

[0075] For example, under low-temperature, high-rate operation at -40℃ and 5C, the capacity loss factor is 0.35, meaning the usable capacity is only 35% of the measured capacity. Under normal-temperature, low-rate operation at 25℃ and 0.5C, the capacity loss factor is 0.99, meaning the usable capacity is close to the measured capacity. For operation conditions between preset temperature points or preset rate points, the capacity loss factor can be obtained through linear interpolation of adjacent preset points.

[0076] In this embodiment of the invention, the current temperature, current, and terminal voltage of the battery are collected. Combined with the DC internal resistance corresponding to the temperature and charge / discharge rate, the terminal voltage is compensated for voltage drop, enabling the compensated voltage to represent the true internal voltage of the battery. When the compensated voltage reaches a preset terminal voltage threshold, a corresponding correction rate is matched based on the difference between the true state of charge (SOC) corresponding to this threshold and the initial SOC obtained by ampere-hour integration. This correction rate is then used as the integration gain for weighted ampere-hour integration, gradually correcting the initial SOC to the true SOC. This reduces the impact of temperature changes and voltage characteristic changes at capacity limits on the displayed SOC, preventing abrupt changes in SOC at high and low temperatures and at capacity limits, achieving a smooth display of the battery's SOC, and solving the technical problem of jumps in battery charge state at high and low temperatures and at capacity limits in existing technologies.

[0077] Figure 4 This is a schematic diagram of a battery state of charge smoothing display device 500 provided in an embodiment of the present invention. The battery state of charge smoothing display device 500 can vary significantly due to different configurations or performance. It may include one or more central processing units (CPUs) 510 and memory 520, and one or more storage media 530 storing application programs 533 or data 532. The memory 520 and storage media 530 can be temporary or persistent storage. The program stored in the storage media 530 may include one or more modules (not shown in the diagram), each module may include a series of instruction operations on the battery state of charge smoothing display device 500. Furthermore, the processor 510 may be configured to communicate with the storage media 530 and execute the series of instruction operations in the storage media 530 on the battery state of charge smoothing display device 500.

[0078] The battery state-of-charge smoothing display device 500 may also include one or more power supplies 540, one or more wired or wireless network interfaces 550, one or more input / output interfaces 560, and / or one or more operating systems 531, such as Windows Server, Mac OS X, Unix, Linux, Free BSD, etc. Those skilled in the art will understand that... Figure 4 The illustrated battery state of charge smoothing display device structure does not constitute a limitation on battery state of charge smoothing display devices, and may include more or fewer components than illustrated, or combine certain components, or have different component arrangements.

[0079] The present invention also provides a computer-readable storage medium, which may be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium, wherein the computer-readable storage medium stores instructions that, when the instructions are executed on a computer, cause the computer to perform the steps of the battery state of charge smoothing display method.

[0080] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0081] Furthermore, although the operations are described in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0082] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A method for smoothly displaying the state of charge of a battery, characterized in that, Including the following steps: Collect the current temperature, current current and terminal voltage of the battery, and perform ampere-hour integration on the current current based on the preset available capacity to obtain the initial state of charge; Based on the current temperature and the charge / discharge rate determined by the current current, the DC internal resistance is retrieved from the preset internal resistance mapping relationship, and the voltage drop compensation is performed on the terminal voltage based on the DC internal resistance and the current current to obtain a compensation voltage that characterizes the true internal voltage of the battery. The compensation voltage is compared with a preset terminal voltage threshold. When the compensation voltage reaches the terminal voltage threshold, a correction rate matching the terminal voltage threshold is determined based on the difference between the actual state of charge and the initial state of charge. Using the correction rate as the integral gain, a weighted ampere-hour integral is performed on the current to correct the initial state of charge to the true state of charge, and the state of charge is obtained and output as a smooth display.

2. The battery state of charge smoothing display method according to claim 1, characterized in that, Before the step of querying the DC internal resistance from the preset internal resistance mapping relationship based on the current temperature and the charge / discharge rate determined by the current current, the following steps are included: Under various temperature and rate combinations consisting of multiple preset temperature points and multiple preset rate points, a pulse current is applied to the battery in a stable voltage state, and the voltage change caused by the pulse current is collected. Based on a preset internal resistance calculation formula, the DC internal resistance is calculated using the voltage change and the pulse current. The internal resistance calculation formula includes: Among them, C r R0(T, C) represents the charge / discharge rate, T represents the temperature, and R0(T, C) represents the charge / discharge rate. r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding DC internal resistance, ΔV is the voltage change caused by the pulse current, I p The amplitude of the pulse current; Based on the mapping relationship between all temperature ratio combinations and DC internal resistance, an internal resistance mapping relationship is constructed.

3. The battery state of charge smoothing display method according to claim 1, characterized in that, The step of using the correction rate as the integral gain to perform a weighted ampere-hour integral operation on the current to correct the initial state of charge to the true state of charge, and obtaining and outputting a smooth display of the state of charge includes: Among them, SOC d (t) represents the smoothed displayed state of charge at time t, SOC0 represents the initial state of charge at the start of the end correction, J represents the correction rate, I(τ) represents the charging and discharging current at time τ, taking a positive value during discharging and a negative value during charging, and C a t represents the available capacity, and t represents the cumulative duration since the start of the end correction.

4. The battery state of charge smoothing display method according to claim 1, characterized in that, The step of compensating the terminal voltage for voltage drop based on the DC internal resistance and the current current to obtain a compensation voltage characterizing the true internal voltage of the battery includes: V 内 =V 端 +R0*I Among them, V 内 The compensation voltage, V, is used to characterize the actual internal voltage of the battery. 端 R0 is the terminal voltage, I is the DC internal resistance, and I is the current.

5. The method for smoothly displaying the state of charge of a battery according to claim 1, characterized in that, The step of determining a correction rate matching the state of charge difference based on the state of charge difference between the actual state of charge corresponding to the terminal voltage threshold and the initial state of charge includes: The absolute value of the state of charge difference is matched with several preset continuous numerical intervals to obtain a correction rate that matches the state of charge difference. Each numerical interval corresponds to a different correction rate, and the larger the value of the numerical interval, the larger the corresponding correction rate.

6. The method for smoothly displaying the state of charge of a battery according to claim 1, characterized in that, After the step of performing a weighted ampere-hour integral operation on the current using the correction rate as the integral gain to correct the initial state of charge to the true state of charge, and obtaining and outputting a smooth display of the state of charge, the method further includes: In response to the completion of a complete charge-discharge cycle, the measured capacity corresponding to the complete charge-discharge cycle is collected. Based on the measured capacity and the capacity loss coefficient associated with the current temperature and the charge-discharge rate, the available capacity is updated to obtain the updated available capacity. The updated available capacity is then used as the reference capacity for the next ampere-hour integration calculation.

7. The method for smoothly displaying the state of charge of a battery according to claim 6, characterized in that, The steps for collecting the measured capacity corresponding to the complete charge-discharge cycle include: The charging and discharging current is integrated over the entire charging and discharging cycle from full charge to vent or from vent to full charge to obtain the measured capacity corresponding to the complete charging and discharging cycle.

8. The method for smoothly displaying the state of charge of a battery according to claim 6, characterized in that, The step of updating the available capacity based on the measured capacity and the capacity loss factor associated with the current temperature and the charge / discharge rate to obtain the updated available capacity includes: Among them, C a For available capacity, C m For the measured capacity, K(T, C) r ( ) represents the relationship between temperature T and charge / discharge rate C r The corresponding capacity loss factor and K(T, C) r )≤1, T is the current temperature, and Cr is the charge / discharge rate.

9. A battery state of charge smoothing display device, characterized in that, The battery state of charge smoothing display device includes: a memory and at least one processor, wherein the memory stores instructions, and the memory and the at least one processor are interconnected via a line; The at least one processor invokes the instructions in the memory to cause the battery state of charge smoothing display device to perform the battery state of charge smoothing display method as described in any one of claims 1-8.

10. A computer-readable storage medium storing a computer program thereon, characterized in that, When the computer program is executed by the processor, it implements the battery state of charge smoothing display method as described in any one of claims 1-8.

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