Lithium iron phosphate battery platform period SOC correction judgment method and device and vehicle
By quantifying the capacity and energy deviations and current sensor deviations during the plateau period of lithium iron phosphate batteries, and combining ampere-hour and watt-hour integration, the problem of inaccurate SOC calculation in traditional methods is solved, achieving timely and accurate SOC correction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NEUSOFT REACH AUTOMOBILE TECH (SHENYANG) CO LTD
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-05
AI Technical Summary
Calculating the state of charge (SOC) of lithium iron phosphate batteries during the plateau period is difficult, and traditional methods are inaccurate, leading to untimely correction.
By determining the deviation between capacity and energy and the deviation of the current sensor, and combining the ampere-hour integral and watt-hour integral, the SOC deviation is quantified, and a correction warning signal is sent when the deviation exceeds the threshold.
This improves the timeliness and accuracy of SOC correction during the plateau period of lithium iron phosphate batteries, ensuring the accurate determination and timely correction of SOC deviation analysis.
Smart Images
Figure CN121978561A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle technology, and in particular to a method, device and vehicle for determining the SOC correction during the plateau period of a lithium iron phosphate battery. Background Technology
[0002] The State of Charge (SOC) calculation of lithium iron phosphate (LFP) batteries is difficult, mainly because the voltage of LFP batteries tends to plateau. Within this range, voltage fluctuations are small when the SOC changes, which does not meet the linearity requirement. This leads to inaccurate SOC calculations using traditional methods (such as combining Kalman filtering with ampere-hour integration) for batteries that meet the linearity requirement. Consequently, corrections are only performed when the SOC deviation is large, resulting in untimely corrections. Summary of the Invention
[0003] In view of this, this application provides a method, apparatus and vehicle for judging the SOC correction during the plateau period of lithium iron phosphate batteries, aiming to improve the timeliness of SOC correction during the plateau period of lithium iron phosphate batteries.
[0004] Firstly, this application provides a method for determining the SOC correction during the plateau period of a lithium iron phosphate battery, including: The deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period is determined as the first deviation; The cumulative deviation of the current sensor during the sampling process in the plateau period is determined as the second deviation; Based on the first deviation and the second deviation, the SOC deviation is determined. When the SOC deviation exceeds the deviation threshold, an early warning signal to perform SOC correction is sent.
[0005] Optionally, determining the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period includes: Starting from the most recent SOC calibration, the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy is accumulated during each plateau period, and the discharge deviation between the SOC value corresponding to the discharging capacity and the SOC value corresponding to the discharging energy is accumulated during each discharging period to determine the first deviation corresponding to the current SOC.
[0006] Optionally, the method for calculating the charging deviation between the charging capacity and the charging energy for each charge includes: Based on the current sampling value and the ampere-hour integral, the charging capacity corresponding to the plateau period at the given temperature is determined; Based on the first correspondence between the charging capacity and the temperature at which the charging takes place, the SOC value corresponding to the charging capacity during the plateau period is determined. The first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period. Based on the current sampling value, voltage sampling value, and watt-hour integral, the charging energy corresponding to the plateau period at the given temperature is determined. Based on the second correspondence between the charging energy and the temperature at which the charging takes place, the SOC value of the charging during the plateau period is determined. The second correspondence is the correspondence between the charging energy and the SOC value during the plateau period. The difference between the capacity SOC value and the energy SOC value is the charging deviation.
[0007] Optionally, the method for calculating the discharge deviation between the SOC value corresponding to the discharge capacity and the SOC value corresponding to the discharge energy for each discharge includes: Based on the current sampling value and the ampere-hour integral, the discharge capacity corresponding to the discharge during the plateau period is determined; Based on the third correspondence between the discharge capacity and the temperature at which the discharge occurs, the SOC value corresponding to the discharge during the plateau period is determined. The third correspondence is the relationship between the discharge capacity and the SOC value during the plateau period. Based on the current sample value, voltage sample value, and watt-hour integral, the discharge energy corresponding to the discharge during the plateau period is determined; Based on the fourth correspondence between the discharge capacity and the temperature at which the discharge occurs, the SOC value corresponding to the discharge during the plateau period is determined, wherein the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period. The difference between the capacity SOC value and the energy SOC value is the discharge deviation.
[0008] Optionally, determining the cumulative current sensor deviation during the plateau sampling process as the second deviation includes: Starting from the most recent SOC calibration, the cumulative value of the current sensor deviation during each plateau period is accumulated to obtain the second deviation.
[0009] Optionally, the method for calculating the cumulative value of the current sensor deviation during each plateau period is as follows: During charging, a first product of the current sampling deviation value and the charging duration during the plateau period is determined, and a second product of the capacity value and the battery health status is determined; the ratio of the first product to the second product is determined as the cumulative deviation value of the current sensor, wherein the current sampling deviation value is a positive deviation value corresponding to the current sampling value at the temperature corresponding to the charging. In the case of discharge, the third product of the current sampling deviation value and the duration of discharge during the plateau period is determined, and the fourth product of the capacity value and the battery health status is determined; the ratio of the third product to the fourth product is determined as the cumulative deviation value of the current sensor, and the current sampling deviation value is the negative deviation value corresponding to the current sampling value at the temperature corresponding to the discharge. The capacity value is determined based on the SOC value at the corresponding temperature.
[0010] Optionally, the method for determining the plateau period includes: The state of charge (SOC) - open circuit voltage (OCV) curve of lithium iron phosphate battery is determined based on charge and discharge. Determine the plateau threshold based on the target SOC accuracy and voltage sampling accuracy; On the SOC-OCV curve, the interval corresponding to the SOC-OCV ratio being greater than the plateau threshold is the plateau period.
[0011] Optionally, the method further includes: When the lithium iron phosphate battery is charged to the plateau period, the current charging capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a first correspondence at the charging temperature; the first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period; or, the charging energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on a second correspondence at the charging temperature; the second correspondence is the correspondence between the charging energy and the SOC value during the plateau period. When the lithium iron phosphate battery is discharged to the plateau period, the current discharge capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a third correspondence at the temperature where the discharge occurs; the third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period; or, the discharge energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on a fourth correspondence at the temperature where the discharge occurs; the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period at the discharge temperature.
[0012] Secondly, this application provides a lithium iron phosphate battery plateau period SOC correction and judgment device, comprising: The first processing unit is used to determine the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period, as the first deviation; The second processing unit is used to determine the cumulative value of the current sensor deviation during the sampling process of the current sensor in the plateau period as the second deviation; The analysis unit is used to determine the SOC deviation based on the first deviation and the second deviation, and to send an early warning signal to perform SOC correction when the SOC deviation exceeds the deviation threshold.
[0013] Thirdly, this application provides a vehicle that employs the SOC correction judgment method for a lithium iron phosphate battery during the plateau period as described in any one of the above claims, wherein sending a warning signal to perform SOC correction includes: Send a signal to the battery management system instructing the vehicle to fully charge until the vehicle is fully charged.
[0014] This application provides a method, apparatus, and vehicle for determining the SOC correction during the plateau period of a lithium iron phosphate battery. The method includes: determining the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period, as a first deviation; determining the cumulative deviation value of the current sensor during the sampling process of the current sensor during the plateau period, as a second deviation; determining the SOC deviation based on the first deviation and the second deviation; and sending a warning signal to perform SOC correction when the SOC deviation exceeds a deviation threshold. On the one hand, this application determines the first deviation between the capacity and energy during the plateau period. Since energy calculation is less affected by the battery's state of health (SOH) and has strong curve stability, the stability of the energy integral is utilized, upgrading the plateau period SOC analysis from solely relying on current integral to a combination of current integral and energy verification. By analyzing the deviation between the SOCs determined by both capacity and energy, the cumulative degree of deviation of the current lithium iron phosphate battery during the plateau period can be better analyzed. On the other hand, this application also considers the second deviation introduced by the current sensor sampling. Thus, the absolute values of the first and second deviations are superimposed for calculation, covering as many sources of SOC deviation as possible, improving the accuracy and qualitative nature of the deviation analysis, and ensuring the timeliness of subsequent correction. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings used in the description of the embodiment or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 A flowchart illustrating a method for determining the SOC correction during the plateau period of a lithium iron phosphate battery, provided in an embodiment of this application; Figure 2 A schematic diagram of the SOC-OCV curve of a lithium iron phosphate battery provided in an embodiment of this application; Figure 3 A flowchart illustrating an application method for determining the SOC correction during the plateau period of a lithium iron phosphate battery, provided in an embodiment of this application; Figure 4 This is a schematic diagram of a lithium iron phosphate battery plateau period SOC correction and judgment device provided in an embodiment of this application. Detailed Implementation
[0017] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.
[0018] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0019] Unless otherwise stated, the term "multiple" means two or more. In embodiments of this disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B. The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0021] See Figure 1 A flowchart illustrating a method for determining the SOC (State of Charge) during the plateau period of a lithium iron phosphate battery is provided. The method includes: S101. Determine the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period, and take it as the first deviation.
[0022] Preferably, starting from the most recent SOC calibration, the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy is accumulated during each plateau period, and the discharge deviation between the SOC value corresponding to the discharge capacity and the SOC value corresponding to the discharge energy is accumulated during each discharge period to determine the first deviation corresponding to the current SOC.
[0023] Of course, depending on the customer's accuracy requirements, it is also possible to select to only count the first deviation data of the most recent N plateau periods in order to balance calculation efficiency and correction accuracy.
[0024] S102. Determine the cumulative deviation of the current sensor during the sampling process of the current sensor in the plateau period as the second deviation.
[0025] Preferably, the second deviation is obtained by accumulating the cumulative value of the current sensor deviation during each plateau period, starting from the most recent SOC calibration.
[0026] S103. Based on the first deviation and the second deviation, determine the SOC deviation. When the SOC deviation exceeds the deviation threshold, send a warning signal to perform SOC correction.
[0027] Optionally, the SOC deviation can be determined by calculating the sum of the absolute values of the first deviation value and the second deviation value.
[0028] Traditional SOC-OCV correction and the single ampere-hour (Ah) integration method lack accuracy verification standards, resulting in the inability to quantify SOC drift and accurately determine when the deviation threshold is exceeded. This application, based on steps S101-S103, calculates the first deviation between capacity and energy (i.e., the difference between the ampere-hour integrated SOC and the energy integrated SOC) to provide a dual quantitative reference benchmark for the plateau period SOC. Furthermore, it quantifies and compensates for the systematic deviation of the current sensor. Thus, the absolute values of the first and second deviations are superimposed for calculation, covering as many sources of SOC deviation as possible, improving the accuracy and characterization of deviation analysis, and ensuring the timeliness of subsequent correction initiation.
[0029] Based on the above embodiments, the calculation of the first deviation in step S101 can be as follows: starting from the most recent SOC correction, accumulate the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy during each plateau period, and the discharging deviation between the SOC value corresponding to the discharging capacity and the SOC value corresponding to the discharging energy during each discharge, and determine the first deviation corresponding to the current SOC.
[0030] In one possible implementation, the method for calculating the charging capacity and charging energy deviation for each charge includes: Step A1: Based on the current sampling value and ampere-hour integral, determine the charging capacity corresponding to the plateau period at the given temperature.
[0031] Step A2: Based on the first correspondence between the charging capacity and the temperature at which the charging takes place, determine the SOC value of the charging capacity during the plateau period at the given temperature. The first correspondence is the relationship between the charging capacity and the SOC value during the plateau period.
[0032] Step A3: Based on the current sampling value, voltage sampling value, and watt-hour integral, determine the charging energy corresponding to the plateau period at the given temperature.
[0033] Step A4: Based on the second correspondence between the charging energy and the temperature at which the charging takes place, determine the SOC value of the charging energy during the plateau period at the given temperature. The second correspondence is the relationship between the charging energy during the plateau period and the SOC value during the plateau period.
[0034] Step A5: The difference between the charging capacity SOC value and the charging energy SOC value is the charging deviation.
[0035] In one possible implementation, the method for calculating the discharge deviation between the SOC value corresponding to the discharge capacity and the SOC value corresponding to the discharge energy for each discharge includes: Step A1: Based on the current sampling value and the ampere-hour integral, determine the discharge capacity corresponding to the discharge during the plateau period; Step A2: Based on the discharge capacity and the third correspondence, determine the discharge capacity SOC value corresponding to the discharge during the plateau period. The third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period.
[0036] Step A3: Based on the current sampling value, voltage sampling value, and watt-hour integral, determine the discharge energy corresponding to the discharge during the plateau period.
[0037] Step A4: Based on the discharge capacity and the fourth correspondence, determine the discharge energy SOC value corresponding to the discharge during the plateau period. The fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period.
[0038] Step A5: The difference between the discharge capacity SOC value and the discharge energy SOC value is the discharge deviation.
[0039] Furthermore, step S102 above can be used to obtain the second deviation by accumulating the cumulative value of the current sensor deviation during each plateau period from the most recent SOC calibration, which may include: Step C: During charging, determine the first product of the current sampling deviation value and the charging duration during the plateau period, and determine the second product of the capacity value and the battery health status; determine the ratio of the first product to the second product as the cumulative deviation value of the current sensor, wherein the current sampling deviation value is a positive deviation value corresponding to the current sampling value at the temperature corresponding to the charging.
[0040] In the case of discharge, the third product of the current sampling deviation value and the duration of discharge during the plateau period is determined, and the fourth product of the capacity value and the battery health status is determined; the ratio of the third product to the fourth product is determined as the cumulative deviation value of the current sensor, and the current sampling deviation value is the negative deviation value corresponding to the current sampling value at the temperature corresponding to the discharge. The capacity value is determined based on the SOC value at the corresponding temperature.
[0041] In one example, the aforementioned current sampling deviation value can be determined by multiplying the sampling accuracy of the current sensor by the current sampling current value.
[0042] In another example, the aforementioned current sampling deviation value can be determined experimentally by measuring the deviation between the target current value sampled by the current sensor and the target current value at a certain temperature. This deviation is then defined as the current sampling deviation at that temperature. Thus, the current sampling deviation value sampled by the current sensor at the same temperature but different currents can be tested, and then, using interpolation, the current sampling deviation value between different currents at that temperature can be determined. Similarly, the current sampling deviation value sampled by the current sensor at different temperatures for the same current can be tested, and then, using interpolation, the current sampling deviation value between different temperatures at that current can be determined.
[0043] In one possible implementation, the capacity value can be determined in the following way: When the lithium iron phosphate battery is charged to the plateau period, the current charging capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a first correspondence relationship at the temperature where the charging is taking place; the first correspondence relationship is the correspondence relationship between the charging capacity and the SOC value during the plateau period; When the lithium iron phosphate battery is discharged to the plateau period, the current discharge capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on the third correspondence at the temperature where the discharge occurs; the third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period.
[0044] Based on the above embodiments, to determine the plateau period of a lithium iron phosphate battery during charging or discharging, it is first necessary to determine the plateau period in the SOC-OCV curve. Therefore, see [link to relevant documentation]. Figure 2 This diagram illustrates the SOC-OCV curve of a lithium iron phosphate battery. The specific method for determining the plateau period may include: Step D1: Determine the State of Charge (SOC) - Open Circuit Voltage (OCV) curve based on the charge and discharge of the lithium iron phosphate battery; Step D2: Determine the plateau threshold based on the target SOC accuracy and voltage sampling accuracy; Step D3: On the SOC-OCV curve, the interval corresponding to the ratio of SOC to OCV being greater than the plateau threshold is the plateau period.
[0045] The above-mentioned SOC, State of Charge, ranges from 0% to 100%. SOC represents the percentage of the battery's current remaining capacity relative to its rated capacity. 0% indicates a fully discharged battery, and 100% indicates a fully charged battery.
[0046] The aforementioned OCV, Open Circuit Voltage, is the terminal voltage of a battery when it reaches electrochemical equilibrium without charging or discharging current, reflecting the equilibrium potential difference inside the battery.
[0047] In one example, see Figure 2 , Figure 2 The horizontal axis represents SOC (State of Charge), and the vertical axis represents OCV (Optical Value). To determine the plateau period of a lithium iron phosphate battery, if the voltage sampling accuracy is 5mV and the SOC accuracy target is 3%, then the plateau period threshold Δ value = 3% / 5 = 0.6% / mV.
[0048] In the SOC-OCV curve, the region corresponding to a SOC-OCV ratio greater than the plateau threshold Δ is the plateau region (e.g., ...). Figure 2 (in the K2 stage), therefore, as Figure 2 We can determine that the starting point of the platform region is A = 30% SOC, 3.295V; and the ending point is B = 97% SOC, 3.337V.
[0049] Furthermore, when determining whether charging or discharging has entered a plateau period, if the SOC enters the plateau period first and reaches the boundary value (such as 30% SOC or 97% SOC mentioned above), it is still necessary to wait until the OCV reaches the corresponding OCV boundary value (such as 3.295V at point A and 3.337V at point B mentioned above) before confirming that the plateau period has been entered.
[0050] Understandably, in stages K1 and K3, the SOC-OCV curve is a linear curve, and conventional SOC calculation methods, such as Kalman filtering and ampere-hour integration, can still be used. Therefore, this application employs a region-based SOC calculation, while for the plateau period (… Figure 2 The method for calculating SOC in the K2 stage can be: When the lithium iron phosphate battery is charged to the plateau period, the current charging capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a first correspondence at the charging temperature; the first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period; or, the charging energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on a second correspondence at the charging temperature; the second correspondence is the correspondence between the charging energy and the SOC value during the plateau period.
[0051] When the lithium iron phosphate battery is discharged to the plateau period, the current discharge capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on the third correspondence at the temperature where the discharge occurs; the third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period; or, the discharge energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on the fourth correspondence at the temperature where the discharge occurs; the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period.
[0052] Based on the above embodiments, in one possible implementation, the method for determining the first correspondence, second correspondence, third correspondence, and fourth correspondence may include: Step E1: Charge the lithium iron phosphate battery at different temperatures, wherein the charging is performed at least from the beginning of the plateau period to the end of the plateau period. Step E2: Calculate the charging capacity during the plateau period at different temperatures based on the current sampling value and ampere-hour integration; Step E3: Calculate the charging energy during the plateau period at different temperatures based on the current sampling value, voltage sampling value, and watt-hour integral. Step E4: Based on the multiplier corresponding to different temperatures, determine the discharge capacity corresponding to the charging capacity and the discharge energy corresponding to the charging energy at different temperatures. Step E5: Using interpolation, the charging capacity is evenly distributed to each SOC interval within the plateau period to establish a mapping relationship between charging capacity and SOC, resulting in a first correspondence; the charging energy is evenly distributed to each SOC interval within the plateau period to establish a mapping relationship between charging energy and SOC, resulting in a second correspondence; the discharge capacity at different temperatures is evenly distributed to each SOC interval within the plateau period to establish a mapping relationship between discharge capacity and SOC, resulting in a third correspondence at different temperatures; the discharge energy at different temperatures is evenly distributed to each SOC interval within the plateau period to establish a mapping relationship between discharge energy at different temperatures and SOC, resulting in a fourth correspondence.
[0053] The above describes a method for judging the SOC correction during the plateau period of a lithium iron phosphate battery, provided by an embodiment of this application. The following is an exemplary description of this method for judging the SOC correction during the plateau period of a lithium iron phosphate battery, combined with a specific application scenario.
[0054] See Figure 3 The diagram shows a flowchart of a method for determining the SOC correction during the plateau period of a lithium iron phosphate battery. The method includes: S301. Obtain the SOC-OCV curve of the lithium iron phosphate battery and determine the plateau period of the curve.
[0055] The above determination of the plateau period of the curve includes determining the SOC and OCV of the starting point of the plateau period, as well as the SOC and OCV of the ending point.
[0056] Optionally, you can refer to steps D1-D3 above.
[0057] S302. Determine the first correspondence between the plateau period charging capacity and SOC at different temperatures, and determine the second correspondence between the plateau period charging energy and SOC at different temperatures.
[0058] S303. Based on the rate of change corresponding to different temperatures, determine the third correspondence between the plateau discharge capacity and the state of charge (SOC) at different temperatures, and determine the fourth correspondence between the discharge energy during the plateau period and the SOC at different temperatures.
[0059] Optionally, steps S302-S303 above can be referred to steps E1-E5 above.
[0060] S304. Starting from the most recent SOC calibration, accumulate the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy during each plateau period, and the discharge deviation between the SOC value corresponding to the discharging capacity and the SOC value corresponding to the discharging energy during each discharge, and determine the first deviation corresponding to the current SOC.
[0061] Optionally, the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy for each charge can be referred to in steps A1-A5 above, and the discharge deviation between the SOC value corresponding to the discharge capacity and the SOC value corresponding to the discharge energy for each discharge can be referred to in steps B1-B5.
[0062] S305. Starting from the most recent SOC calibration, accumulate the cumulative value of the current sensor deviation during each plateau period to obtain the second deviation.
[0063] Optional, see step C above.
[0064] S306. Take the sum of the absolute values of the first deviation and the second deviation as the SOC deviation, and determine whether the SOC deviation exceeds the deviation threshold.
[0065] S307. If the SOC deviation value exceeds the deviation threshold, a warning signal for performing SOC correction is sent, and the cumulative value in step S304 is reset and recalculated, as well as the cumulative value in step S305 is reset and recalculated.
[0066] S308. If the SOC deviation value does not exceed the deviation threshold, then continue to perform the cumulative calculation in step S304 and the cumulative calculation in step S305.
[0067] The above describes some specific implementations of the SOC correction and judgment method for lithium iron phosphate batteries during the plateau period, as provided in this application. Based on this, this application also provides a corresponding device. The device provided in this application will be described below from the perspective of functional modularity.
[0068] See Figure 4 The diagram shows a structural schematic of a lithium iron phosphate battery plateau period SOC correction and judgment device. The device includes: The first processing unit 401 is used to determine the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period, as the first deviation.
[0069] The second processing unit 402 is used to determine the cumulative value of the current sensor deviation during the sampling process of the current sensor in the plateau period as the second deviation.
[0070] The analysis unit 403 is used to determine the OC deviation based on the first deviation and the second deviation, and to send a warning signal to perform SOC correction when the SOC deviation exceeds the deviation threshold.
[0071] According to the above-mentioned device, the absolute values of the first deviation calculated by the first processing unit and the second deviation calculated by the second processing unit are superimposed to calculate the deviation, which covers the sources of SOC deviation as much as possible, improves the accuracy of deviation analysis and ensures the timeliness of subsequent start-up correction.
[0072] In one specific implementation, the first processing unit 401 is specifically used to accumulate, starting from the most recent SOC correction, the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy during each charging period, and the discharge deviation between the SOC value corresponding to the discharging capacity and the SOC value corresponding to the discharging energy during each discharging period, and determine the first deviation corresponding to the current SOC.
[0073] In one specific implementation, the first processing unit 401 is specifically configured to: determine the charging capacity corresponding to the plateau period at the given temperature based on the current sampling value and the ampere-hour integral; determine the capacity SOC value corresponding to the charging during the plateau period according to a first correspondence between the charging capacity and the temperature at which the charging is taking place, wherein the first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period; determine the charging energy corresponding to the charging during the plateau period at the given temperature based on the current sampling value, the voltage sampling value, and the watt-hour integral; determine the energy SOC value corresponding to the charging during the plateau period according to a second correspondence between the charging energy and the temperature at which the charging is taking place, wherein the second correspondence is the correspondence between the charging energy and the SOC value during the plateau period; and the difference between the capacity SOC value and the energy SOC value is the charging deviation.
[0074] In one specific implementation, the first processing unit 401 is specifically configured to: determine the discharge capacity corresponding to the discharge during the plateau period based on the current sampling value and the ampere-hour integral; determine the capacity SOC value corresponding to the discharge during the plateau period based on a third correspondence between the discharge capacity and the temperature at which the discharge occurs, wherein the third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period; determine the discharge energy corresponding to the discharge during the plateau period based on the current sampling value, the voltage sampling value, and the watt-hour integral; determine the energy SOC value corresponding to the discharge during the plateau period based on a fourth correspondence between the discharge capacity and the temperature at which the discharge occurs, wherein the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period; and the difference between the capacity SOC value and the energy SOC value is the discharge deviation.
[0075] In one possible implementation, the second processing unit 402 is specifically used to accumulate the cumulative value of the current sensor deviation during each plateau period, starting from the most recent SOC calibration, to obtain the second deviation.
[0076] In one possible implementation, the second processing unit 402 is specifically configured to, during charging, determine a first product of the current sampling deviation value and the charging duration during the plateau period, and a second product of the capacity value and the battery health state; determine the ratio of the first product to the second product as the cumulative deviation value of the current sensor, wherein the current sampling deviation value is a positive deviation value corresponding to the current sampling value at the temperature corresponding to the charging; during discharging, determine a third product of the current sampling deviation value and the discharging duration during the plateau period, and a fourth product of the capacity value and the battery health state; determine the ratio of the third product to the fourth product as the cumulative deviation value of the current sensor, wherein the current sampling deviation value is a negative deviation value corresponding to the current sampling value at the temperature corresponding to the discharging; the capacity value is a value determined based on the SOC value at the corresponding temperature.
[0077] In one possible implementation, the device further includes a plateau period unit, which is used to determine the state of charge (SOC)-open circuit voltage (OCV) curve based on the charge and discharge of the lithium iron phosphate battery; determine a plateau period threshold based on the target SOC accuracy and voltage sampling accuracy; and define the interval on the SOC-OCV curve where the ratio of SOC to OCV is greater than the plateau period threshold as the plateau period.
[0078] In one possible implementation, the device further includes a determining unit, configured to, when the lithium iron phosphate battery is charged to the plateau period, calculate the current charging capacity based on current sampling values and ampere-hour integrals, and determine the current SOC value based on a first correspondence at the charging temperature; the first correspondence being the correspondence between charging capacity and SOC value during the plateau period; or, calculate the charging energy during the plateau period based on current sampling values, voltage sampling values, and watt-hour integrals, and determine the current SOC value based on a second correspondence at the charging temperature; the second correspondence being the plateau period's charging energy. The relationship between charging energy and SOC value during the period; when the lithium iron phosphate battery is discharged to the plateau period, the current discharge capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on the third relationship at the temperature where the discharge occurs; the third relationship is the relationship between discharge capacity and SOC value during the plateau period; or, the discharge energy during the plateau period is calculated based on the current sampling value, voltage sampling value and watt-hour integral, and the current SOC value is determined based on the fourth relationship at the temperature where the discharge occurs, the fourth relationship is the relationship between discharge energy and SOC value during the plateau period.
[0079] This application also provides corresponding vehicles and computer storage media for implementing the solutions provided in this application.
[0080] The vehicle employs a SOC correction judgment method for a lithium iron phosphate battery during its plateau period, as described in any of the above embodiments. The method includes sending a warning signal to perform SOC correction, comprising: Send a signal to the battery management system instructing the vehicle to fully charge until the vehicle is fully charged.
[0081] Understandably, if there are other interferences, such as an external power outage, the signal can continue to be sent until the vehicle is fully charged.
[0082] The computer storage medium stores code. When the code is executed, the device running the code implements a method for determining the SOC correction of a lithium iron phosphate battery during its plateau period, as described in any embodiment of this application.
[0083] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.
[0084] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that all or part of the steps in the methods of the above embodiments can be implemented by means of software plus a general-purpose hardware platform. Based on this understanding, the technical solution of this application can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as a read-only memory (ROM) / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network communication device such as a router) to execute the methods described in various embodiments or some parts of the embodiments of this application.
[0085] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.
[0086] The above description is merely an exemplary implementation of this application and is not intended to limit the scope of protection of this application.
Claims
1. A method for judging the SOC correction during the plateau period of a lithium iron phosphate battery, characterized in that, include: The deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period is determined as the first deviation; The cumulative deviation of the current sensor during the sampling process in the plateau period is determined as the second deviation; Based on the first deviation and the second deviation, the SOC deviation is determined. When the SOC deviation exceeds the deviation threshold, an early warning signal to perform SOC correction is sent.
2. The method according to claim 1, characterized in that, The determination of the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period includes: Starting from the most recent SOC calibration, the charging deviation between the SOC value corresponding to the charging capacity and the SOC value corresponding to the charging energy is accumulated during each plateau period, and the discharge deviation between the SOC value corresponding to the discharging capacity and the SOC value corresponding to the discharging energy is accumulated during each discharging period to determine the first deviation corresponding to the current SOC.
3. The method according to claim 2, characterized in that, The method for calculating the charging capacity and charging energy deviation for each charge includes: Based on the current sampling value and the ampere-hour integral, the charging capacity corresponding to the plateau period at the given temperature is determined; Based on the first correspondence between the charging capacity and the temperature at which the charging takes place, the SOC value corresponding to the charging capacity during the plateau period is determined. The first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period. Based on the current sampling value, voltage sampling value, and watt-hour integral, the charging energy corresponding to the plateau period at the given temperature is determined. Based on the second correspondence between the charging energy and the temperature at which the charging takes place, the SOC value of the charging during the plateau period is determined. The second correspondence is the correspondence between the charging energy and the SOC value during the plateau period. The difference between the capacity SOC value and the energy SOC value is the charging deviation.
4. The method according to claim 3, characterized in that, The method for calculating the discharge deviation between the SOC value corresponding to the discharge capacity and the SOC value corresponding to the discharge energy for each discharge includes: Based on the current sampling value and the ampere-hour integral, the discharge capacity corresponding to the discharge during the plateau period is determined; Based on the third correspondence between the discharge capacity and the temperature at which the discharge occurs, the SOC value corresponding to the discharge during the plateau period is determined. The third correspondence is the relationship between the discharge capacity and the SOC value during the plateau period. Based on the current sample value, voltage sample value, and watt-hour integral, the discharge energy corresponding to the discharge during the plateau period is determined; Based on the fourth correspondence between the discharge capacity and the temperature at which the discharge occurs, the SOC value corresponding to the discharge during the plateau period is determined, wherein the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period. The difference between the capacity SOC value and the energy SOC value is the discharge deviation.
5. The method according to claim 1, characterized in that, The determination of the cumulative deviation of the current sensor during the plateau sampling process as the second deviation includes: Starting from the most recent SOC calibration, the cumulative value of the current sensor deviation during each plateau period is accumulated to obtain the second deviation.
6. The method according to claim 5, characterized in that, The method for calculating the cumulative value of the current sensor deviation during each plateau period is as follows: During charging, a first product of the current sampling deviation value and the charging duration during the plateau period is determined, and a second product of the capacity value and the battery health status is determined; the ratio of the first product to the second product is determined as the cumulative deviation value of the current sensor, wherein the current sampling deviation value is a positive deviation value corresponding to the current sampling value at the temperature corresponding to the charging. In the case of discharge, the third product of the current sampling deviation value and the duration of discharge during the plateau period is determined, and the fourth product of the capacity value and the battery health status is determined; the ratio of the third product to the fourth product is determined as the cumulative deviation value of the current sensor, and the current sampling deviation value is the negative deviation value corresponding to the current sampling value at the temperature corresponding to the discharge. The capacity value is determined based on the SOC value at the corresponding temperature.
7. The method according to claim 1, characterized in that, The method for determining the plateau period includes: The state of charge (SOC) - open circuit voltage (OCV) curve of lithium iron phosphate battery is determined based on charge and discharge. Determine the plateau threshold based on the target SOC accuracy and voltage sampling accuracy; On the SOC-OCV curve, the interval corresponding to the SOC-OCV ratio being greater than the plateau threshold is the plateau period.
8. The method according to claim 7, characterized in that, The method further includes: When the lithium iron phosphate battery is charged to the plateau period, the current charging capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a first correspondence at the charging temperature; the first correspondence is the correspondence between the charging capacity and the SOC value during the plateau period; or, the charging energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on a second correspondence at the charging temperature; the second correspondence is the correspondence between the charging energy and the SOC value during the plateau period. When the lithium iron phosphate battery is discharged to the plateau period, the current discharge capacity is calculated based on the current sampling value and the ampere-hour integral, and the current SOC value is determined based on a third correspondence at the temperature where the discharge occurs; the third correspondence is the correspondence between the discharge capacity and the SOC value during the plateau period; or, the discharge energy during the plateau period is calculated based on the current sampling value, the voltage sampling value, and the watt-hour integral, and the current SOC value is determined based on a fourth correspondence at the temperature where the discharge occurs; the fourth correspondence is the correspondence between the discharge energy and the SOC value during the plateau period at the discharge temperature.
9. A device for judging the SOC correction during the plateau period of a lithium iron phosphate battery, characterized in that, include: The first processing unit is used to determine the deviation between the SOC value corresponding to the current charging or discharging capacity and the SOC value corresponding to the energy during the plateau period, as the first deviation; The second processing unit is used to determine the cumulative value of the current sensor deviation during the sampling process of the current sensor in the plateau period as the second deviation; The analysis unit is used to determine the SOC deviation based on the first deviation and the second deviation, and to send an early warning signal to perform SOC correction when the SOC deviation exceeds the deviation threshold.
10. A vehicle, characterized in that, The method for determining the SOC correction of a lithium iron phosphate battery during its plateau period, as described in any one of claims 1-8, includes sending a warning signal for performing SOC correction, comprising: Send a signal to the battery management system instructing the vehicle to fully charge until the vehicle is fully charged.