A method, device, equipment and medium for identifying an end of a battery platform area

Abstract

The application discloses a battery platform area end identification method, device and equipment and medium, and relates to the technical field of automobile electronics, and the method comprises the following steps: acquiring a real-time running state of a battery pack to be detected, determining a lowest single cell voltage according to the real-time running state, correcting the lowest single cell voltage according to the real-time running state, and obtaining a corrected voltage; calibrating a reference inflection point threshold of the battery pack to be detected offline; determining a slope of the corrected voltage relative to cumulative discharge capacity in a preset sliding window, obtaining a corrected voltage slope corresponding to each sliding window, and determining whether the battery pack to be detected enters a platform area end judgment interval; constructing a future request current trajectory, predicting a terminal voltage at a future time according to the future request current trajectory, and determining an actual running inflection point according to the terminal voltage at the future time. The application realizes online accurate identification of an actual inflection point of a battery pack discharge process platform area end under load, aging and variable temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of automotive electronics technology, and more specifically to a method, apparatus, device, and medium for identifying the end of a battery platform region. Background Technology

[0002] Lithium iron phosphate batteries have been widely used in electric vehicles, energy storage systems and low-voltage vehicle power supplies due to their advantages of high safety, long cycle life and low cost.

[0003] Lithium iron phosphate (LFP) batteries exhibit a prolonged plateau region, and the inflection point at the end of this plateau is often used to determine whether undervoltage protection during the discharge period is necessary. Within the plateau region, the battery voltage changes very little, but the state of charge (SOC) changes relatively significantly. At the end of the plateau, the battery voltage drops sharply as the SOC decreases. This electrochemical characteristic of the plateau region makes identifying the inflection point at the end of the discharge plateau a key technical challenge for battery management systems (BMS), especially under load, aging, and variable temperature conditions, where existing fixed SOC or voltage thresholds are even more difficult to use for online identification.

[0004] Therefore, accurately identifying the inflection point at the end of the discharge plateau of lithium iron phosphate batteries and reliably performing undervoltage protection is an important issue that the industry urgently needs to address. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method, apparatus, device and medium for identifying the end of the battery platform region, thereby solving the problem that using a fixed SOC threshold or a fixed voltage threshold cannot accurately identify the inflection point at the end of the discharge platform of a lithium iron phosphate battery under load, aging and variable temperature conditions.

[0006] According to a first aspect, embodiments of the present invention provide a method for identifying the end of a battery platform region, the method comprising: The system acquires the real-time operating status of the battery pack under test, determines the minimum single-cell voltage based on the real-time operating status, and performs load correction on the minimum single-cell voltage based on the real-time operating status to obtain the corrected voltage. The real-time operating status includes real-time battery voltage, battery current, battery temperature, state of charge, and battery health status. The reference inflection point threshold of the battery pack under test is calibrated offline. Determine the slope of the correction voltage relative to the cumulative discharge capacity within the preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be tested has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold. Once the platform zone's final judgment interval is determined, a future request current trajectory is constructed. Based on this trajectory, the terminal voltage at future times is predicted. The state of charge at future times is predicted when the terminal voltage reaches the sum of the preset undervoltage protection threshold and the safety margin threshold. The corresponding state of charge at future times is then determined as the actual operating inflection point.

[0007] According to a second aspect, embodiments of the present invention also provide an identification device for the end of a battery platform region, the device comprising: The load correction module is used to acquire the real-time operating status of the battery pack under test, determine the minimum single cell voltage based on the real-time operating status, and perform load correction on the minimum single cell voltage based on the real-time operating status to obtain the corrected voltage; the real-time operating status includes real-time battery voltage, battery current, battery temperature, state of charge, and battery health status. The offline calibration module is used to calibrate the reference inflection point threshold of the battery pack under test offline. The interval identification module is used to determine the slope of the correction voltage relative to the cumulative discharge capacity within a preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be detected has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold. The inflection point identification module is used to construct the future request current trajectory when the end judgment interval of the platform area is determined, predict the terminal voltage at the future time based on the future request current trajectory, and predict the state of charge at the future time when the terminal voltage at the future time reaches the sum of the preset undervoltage protection threshold and the safety margin threshold, and determine the state of charge at the corresponding future time as the actual operating inflection point.

[0008] According to a third aspect, embodiments of the present invention also provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the battery platform region end identification method as described above.

[0009] According to a fourth aspect, embodiments of the present invention also provide a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the battery platform region end identification method as described above.

[0010] The present invention discloses a method, apparatus, device, and medium for identifying the end of the battery platform region. It determines the lowest single-cell voltage based on real-time operating conditions and performs load correction on the lowest single-cell voltage based on real-time operating conditions to obtain a corrected voltage. Then, it extracts the corrected voltage slope reflecting the actual electrochemical state change from the terminal voltage affected by the coupled influence of load, aging, and temperature factors. The corrected voltage slope is then compared with a reference inflection point threshold of the battery pack under test, calibrated offline, to distinguish between load voltage drop and the actual SOC end voltage drop. Furthermore, it incorporates future load changes into the inflection point determination through forward voltage prediction, matching the protection strategy with actual operating conditions. This achieves accurate online identification of the actual inflection point at the end of the battery pack's discharge platform region under load, aging, and variable temperature conditions, solving the problem that fixed threshold methods cannot adapt to changes in actual operating conditions. Attached Figure Description

[0011] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings: Figure 1 A flowchart illustrating the method for identifying the end of the battery platform region provided by the present invention is shown. Figure 2 The diagram illustrates the trend identification of the corrected voltage, the original single-cell voltage, and the end of the platform region in the battery platform region identification method provided by the present invention. Figure 3 A schematic diagram of the applied power-on pulse in the battery platform region end identification method provided by the present invention is shown; Figure 4 This diagram illustrates the method for identifying the end of a battery platform region provided by the present invention, which utilizes a sliding window to calculate the corrected voltage slope. Figure 5 This diagram illustrates a pulse representation of the future requested current trajectory in the battery platform region end identification method provided by the present invention. Figure 6 A schematic diagram of the structure of the identification device at the end of the battery platform area provided by the present invention is shown; Figure 7 A schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] Lithium iron phosphate (LFP) batteries exhibit a significant plateau characteristic between their open-circuit voltage and state of charge (SOC): LFP batteries maintain a prolonged plateau (within the SOC range of approximately 20% to 80%), during which voltage changes are minimal while SOC changes are relatively large. At the end of this plateau (below approximately 20% SOC), the battery voltage decreases sharply as SOC decreases. This inflection point at the end of the plateau (i.e., the critical point at the end of the plateau) is often used to determine whether undervoltage protection during the discharge period is necessary, such as undervoltage protection in parking mode.

[0014] The existing BMS identification platform mainly determines the inflection point at the end of the area by using SOC or battery voltage. For example, when the SOC of the battery pack is less than a certain voltage threshold (such as 10%), the point is considered to be the inflection point, and the battery pack needs to be under-voltage protected accordingly. Alternatively, when the battery voltage of the battery pack is less than a certain voltage threshold (such as 2.5V), the point is considered to be the inflection point, and the battery pack needs to be under-voltage protected accordingly, and power limiting or power-off operations are subsequently performed.

[0015] However, battery aging leads to a decrease in usable capacity, resulting in less usable capacity at the same SOC. The actual SOC value corresponding to the inflection point increases. If a fixed SOC threshold is still used to identify the inflection point, it will cause undervoltage protection to be triggered prematurely or delayed. Specifically: ; in, This indicates the actual usable capacity of the battery pack under current aging conditions; Indicates the rated capacity of the battery pack; This indicates the battery pack's State of Health (SOH) calculated based on its capacity, which is also known as capacity-based health.

[0016] The terminal voltage of a lithium iron phosphate battery is specifically composed of the open-circuit voltage, ohmic voltage drop, and polarization voltage. Specifically: ; in, This indicates the terminal voltage of a lithium iron phosphate battery. This indicates the open-circuit voltage of a lithium iron phosphate battery. This represents the discharge current during the discharge process of a lithium iron phosphate battery. This indicates the ohmic internal resistance of a lithium iron phosphate battery. This indicates the polarization voltage of a lithium iron phosphate battery.

[0017] According to this calculation formula, it can be seen that a fixed voltage threshold cannot determine whether the drop in terminal voltage comes from a decrease in SOC, or from an increase in current voltage drop, polarization voltage drop, or ohmic internal resistance.

[0018] Under load conditions, a large discharge current generates a significant ohmic voltage drop and polarization voltage across the internal resistance of the lithium iron phosphate battery. These load effects cause the terminal voltage to deviate severely from the off-circuit voltage. When the discharge current is large, such as during the acceleration of an electric vehicle, the ohmic voltage drop can reach hundreds of millivolts, which is enough to mask the true low-charge decline trend at the end of the plateau region. For example, an increase in the ohmic voltage drop at the same current causes the terminal voltage to approach the undervoltage protection threshold earlier. In addition, as the battery ages, capacity decay and internal resistance increase, causing the available energy and voltage margin to drift. Temperature changes simultaneously affect the open-circuit voltage characteristics, internal resistance, and polarization. Under the combined effect of these multiple factors, identifying the inflection point by the battery voltage falling below a fixed voltage threshold cannot distinguish between a true low-charge condition and a load voltage drop in the lithium iron phosphate battery. If the inflection point is still identified based on a fixed voltage threshold, it will also lead to premature or delayed triggering of undervoltage protection.

[0019] Meanwhile, because the voltage change of lithium iron phosphate batteries is relatively gradual in the plateau region, the slope of the open-circuit voltage-state-of-charge (OCV-SOC) curve is small, and the terminal voltage is less sensitive to changes in SOC. Therefore, under online operating conditions, the original terminal voltage is easily affected by sampling noise, load fluctuations, temperature changes, and internal resistance voltage drop. Directly detecting the inflection point on the original voltage curve can easily misjudge disturbances as true characteristics.

[0020] It should also be noted that the terminal voltage collected by the BMS during online operation is not the ideal open-circuit voltage, but rather the loaded terminal voltage superimposed with the ohmic voltage drop caused by the discharge current, polarization voltage drop, temperature effects, sampling noise, and load transient fluctuations. Since the actual voltage change in the plateau region is small, the above disturbances may be on a similar order of magnitude to the voltage change caused by the SOC change. If the first-order slope or second-order curvature is directly detected on the original terminal voltage curve, noise, load changes, or temperature changes are easily misjudged as the inflection point at the end of the discharge plateau. Temperature changes simultaneously affect the open-circuit voltage characteristics (the overall OCV increases but the plateau region is narrower at low temperatures), the internal resistance (the internal resistance increases significantly at low temperatures), and the degree of polarization, causing the actual inflection point position at the end of the plateau to drift significantly with operating conditions, aging state, and temperature. The fixed threshold method cannot adapt to this drift.

[0021] In summary, accurately identifying the inflection point at the end of the discharge plateau of lithium iron phosphate batteries and reliably implementing undervoltage protection is an important issue that the industry urgently needs to address.

[0022] To address the aforementioned issues, this specification provides a method for identifying the end of a battery plateau region, aiming to achieve accurate online identification of the actual inflection point at the end of the plateau region during the battery pack discharge process under load, aging, and variable temperature conditions. The method for identifying the end of the battery plateau region provided in this specification can be applied to electronic devices, including laptops, desktop computers, smartphones, smart wearable devices, tablets, etc. Furthermore, the method for identifying the end of the battery plateau region provided in this specification can also be applied to applications running on the aforementioned electronic devices. Figure 1 This is a flowchart illustrating a method for identifying the end of a battery platform region according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps: S101. Obtain the real-time operating status of the battery pack to be tested, determine the minimum single-cell voltage based on the real-time operating status, and perform load correction on the minimum single-cell voltage based on the real-time operating status to obtain the corrected voltage. The real-time operating status includes real-time battery voltage, battery current, battery temperature, SOC, and SOH.

[0023] Please see Figure 2 , Figure 2 The graphs show the lowest single-cell voltage (i.e., the original single-cell voltage), the corrected voltage, and the curves corresponding to the end-trend identification line. The area to the right of the end-trend identification line is the plateau region's end-judgment interval, where the end-trend of the plateau region is more easily identified. The battery voltage acquired online by the BMS is a loaded terminal voltage superimposed with ohmic voltage drop, polarization voltage drop, load transients, and sampling noise. The battery voltage includes the cell voltages corresponding to each cell in the battery pack under test, which are connected in series. The lowest single-cell voltage (i.e., the original single-cell voltage) can be determined based on the cell voltage. However, directly calculating the first-order slope or second-order curvature from the original single-cell voltage can misjudge load disturbances as curve inflection points.

[0024] In this embodiment, the lowest single cell voltage is adjusted based on the real-time operating status to eliminate the load effect caused by noise and disturbances in the terminal voltage as much as possible. The adjustment voltage changes with SOC more closely to the open circuit voltage characteristic, thus showing a clear voltage drop trend at the end of the plateau region, providing a reliable data basis for subsequent slope identification.

[0025] S102. The reference inflection point threshold of the battery pack under test is calibrated offline.

[0026] Before the battery pack under test is put into operation, an offline calibration test is performed on a lithium iron phosphate battery pack of the same model as the battery pack under test. The offline calibration process selects representative cell samples covering different aging states and temperature conditions, and performs constant current discharge at a rate lower than the preset rate (e.g., 0.05C to 0.2C) from the initial state of charge of 100% until the preset cutoff voltage (e.g., 2V). The battery voltage and actual usable capacity of the cell sample at each time point are recorded throughout the discharge process.

[0027] By discharging at a low rate, the ohmic voltage drop and polarization voltage are both at a minimum level. This makes the terminal voltage during the offline calibration process close to the open-circuit voltage, thus obtaining a battery voltage-capacity (VQ) discharge curve with approximately open-circuit voltage characteristics.

[0028] The reference inflection point threshold of the battery pack under test can be extracted based on the slope of the battery voltage-capacity discharge curve.

[0029] S103. Determine the slope of the correction voltage relative to the cumulative discharge capacity within the preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be tested has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold.

[0030] In this embodiment, the slope of the corrected voltage relative to the cumulative discharge capacity is determined within a sliding window to obtain the corrected voltage slope. The sliding window employs a dual-window mechanism, with a capacity window as the primary window and a time window as the secondary window. The size of the capacity window is determined based on the cell capacity of the battery pack to be tested and the required accuracy.

[0031] The time window serves as an auxiliary mechanism to ensure timely updates of the slope in low-current, long-term operation scenarios. When the capacity window fails to accumulate sufficient capacity changes within the set time window, the slope calculation is triggered by the time window.

[0032] The calculated corrected voltage slope is compared with the reference inflection point threshold calibrated offline in step S102. When the corrected voltage slope is not lower than the reference inflection point threshold, the battery is confirmed to have entered the end judgment interval of the plateau region.

[0033] Meanwhile, through a continuous multiple confirmation mechanism, false judgments caused by the slope momentarily exceeding the threshold due to current fluctuations, sampling noise, or instantaneous disturbances are effectively suppressed. Only when the corrected voltage slope stably exceeds the reference inflection point threshold within multiple consecutive sliding windows is it considered to truly reflect the transition of the electrochemical state, thereby improving the reliability of inflection point identification.

[0034] S104. When it is determined that the platform area is entering the final judgment interval, the future request current trajectory is constructed, the terminal voltage at the future time is predicted based on the future request current trajectory, and the state of charge at the future time is predicted when the terminal voltage at the future time reaches the sum of the preset undervoltage protection threshold and the safety margin threshold, and the state of charge at the corresponding future time is determined as the actual operating inflection point.

[0035] In this embodiment, the future requested current trajectory is constructed based on the following information: current vehicle power request (from vehicle controller or driver input), DC / DC converter load, thermal management load, drive load, historical power change rate, conservative margin, and safety conservative strategy. This information belongs to the vehicle's load power supply information. When the BMS obtains any one or a combination of the above information, in order to ensure that the vehicle can still operate normally and safely under the scenario requirements corresponding to the above information, the future requested current trajectory is constructed accordingly.

[0036] Specifically, the formula for predicting the terminal voltage at future times based on the future requested current trajectory is as follows: ; in, Indicates the first The terminal voltage at time t, the first The time in question is a future moment equivalent to the present moment, not a historical moment. Indicates the time-domain variable for prediction. , Indicates the forecast time window; This indicates that based on battery temperature, SOH, and the first The open-circuit voltage predicted at time SOC. , Indicates the first SOC at any moment Indicates battery temperature; Indicates the first The battery current at a given moment can be used to determine the battery current corresponding to each future moment in the trajectory based on the future requested current trajectory. This represents the compensated ohmic internal resistance. Specifically, the real-time ohmic internal resistance is compensated based on battery temperature, state of charge, and battery health status to obtain the parameters. ; Indicates the first Polarization voltage at time, parameters It can be obtained by constructing an equivalent circuit model and then recursively determining it using the equivalent circuit model.

[0037] In the embodiments of this application, parameters It is also determined by the preset undervoltage protection threshold and the preset safety margin threshold, specifically; ; in, Indicates the undervoltage protection threshold; Indicates the safety margin threshold, parameter It is used to cover sampling errors, internal resistance estimation errors, model errors, and temperature imbalances.

[0038] parameter The specific values ​​can be determined based on error analysis. For example, the sampling error is approximately ±5mV, the internal resistance estimation error is approximately ±10%, corresponding to a voltage drop error of approximately ±20mV, the model error is approximately ±20mV, and the temperature imbalance error is approximately ±10mV. These error source parameters are considered together. The value range is from 50mV to 100mV, and the parameter is ultimately... Set to 0.08V.

[0039] parameter and parameters All of these can be preset, for example, setting Set to 2.8V, Set to 0.08V. That is, 2.88V.

[0040] because , , All of these can be calculated through other methods, and can be satisfied by reverse-engineering the future requested current trajectory. of as well as corresponding Then, the determined results will be calculated in reverse. The corresponding SOC value serves as the actual operating inflection point, and the BMS can implement graded undervoltage protection using this actual operating inflection point.

[0041] Since the State of Charge (SOC) value of a battery continuously decreases during discharge, in this embodiment, based on the future requested current trajectory and the real-time SOC, the system scans from the real-time SOC (i.e., the current remaining SOC) towards lower SOC levels to solve for the parameters that make the above equation hold true. The value of .

[0042] Simultaneously, it can determine the safety margin and continuously monitor the rate of change of the safety margin. When the safety margin continues to decrease within the predicted time window and the rate of decrease exceeds a preset threshold, it indicates that the battery voltage is rapidly approaching the undervoltage boundary, requiring protective measures to be taken in advance. This trend monitoring provides time dimension information on how much time is left before a problem occurs, making the protection action predictable.

[0043] The battery platform region end identification method of the present invention determines the lowest single cell voltage based on the real-time operating status, and performs load correction on the lowest single cell voltage based on the real-time operating status to obtain a corrected voltage. Then, it extracts the corrected voltage slope reflecting the actual electrochemical state change from the terminal voltage affected by the coupling of load, aging and temperature factors. The corrected voltage slope is then compared with the reference inflection point threshold of the battery pack under test through offline calibration, thereby distinguishing between load voltage drop and the actual SOC end voltage drop. Furthermore, future load changes are incorporated into the inflection point determination through forward voltage prediction, so that the protection strategy matches the actual operating conditions. This achieves online accurate identification of the actual inflection point at the end of the battery pack discharge process under load, aging and variable temperature conditions, and solves the problem that the fixed threshold method cannot adapt to changes in actual operating conditions.

[0044] In this embodiment of the application, step S101 specifically includes: S1011. Obtain the real-time operating status of the battery pack under test, that is, obtain the online real-time battery voltage, battery current, battery temperature, SOC and SOH.

[0045] In this embodiment, the real-time State of Health (SOH) can be determined using the capacity decay method based on the real-time operating status. The capacity decay method calculates the capacity retention rate by comparing the current actual usable capacity of the battery pack with its nominal rated capacity, thereby obtaining the real-time SOH. By recording the accumulated ampere-hour data from each charge-discharge cycle, the current usable capacity is fitted to the data. Then, based on the nominal rated capacity of the battery pack at the time of manufacture, the current usable capacity is divided by the nominal rated capacity and multiplied by 100% to obtain the real-time SOH.

[0046] In the embodiments of this application, the real-time SOC can be determined by using the open-circuit voltage method, Kalman filtering based on the equivalent circuit model, or ampere-hour integration method, according to the real-time operating status.

[0047] In particular, as the real-time SOH estimate is continuously updated based on the real-time operating status, the capacity parameter in the ampere-hour integral is replaced with the updated SOH. That is, the capacity parameter in the ampere-hour integral uses the latest SOH. In this way, even if the battery pack ages, the percentage change in SOC corresponding to the same ampere-hour integral will be greater, ensuring that the determined real-time SOC is as consistent as possible with the actual remaining usable power.

[0048] It should be noted that other methods can also be used to determine the real-time SOC and SOH. The specific method depends on the BMS's operating strategy and the actual algorithm embedded in the BMS. Here, no restrictions are placed on the method for determining the real-time SOC and SOH, as long as the real-time SOC and SOH can be obtained based on the various parameters in the actual operating state.

[0049] S1012. Determine the lowest real-time cell voltage of the battery pack to be tested based on the real-time battery voltage.

[0050] The battery pack to be tested consists of several cells connected in series. Therefore, the obtained battery voltage includes the cell voltage corresponding to each cell. The minimum value of the cell voltage is taken as the real-time lowest single cell voltage.

[0051] It should be noted that the real-time battery voltage obtained is the terminal voltage. Similarly, the cell voltage corresponding to each cell and the lowest single cell voltage determined based on the cell voltage of each cell are also terminal voltages.

[0052] S1013. Process the battery voltage and battery current based on the power-on pulse during vehicle startup, and extract the real-time internal resistance of the battery pack to be tested.

[0053] Please see Figure 3 During the start-up process of a vehicle equipped with a battery pack under test, a power-on pulse is applied to the battery pack. This power-on pulse is a current step that naturally occurs during normal vehicle power-on, pre-charging, DC / DC start-up, or high-voltage accessory start-up. The BMS can use the voltage and current changes before and after the step to estimate the current equivalent ohmic internal resistance. Specifically: ; in, Indicates the internal resistance of the ohm; This represents the first pulse voltage value, which is also the lowest single-cell voltage of the battery pack under test within a short time window after the power-on pulse is established. To avoid polarization effects, the parameter... It is necessary to prioritize short time windows following the pulse step rather than steady-state voltage after a long time. This represents the second pulse voltage value, which is also the lowest single-cell voltage of the battery pack under test within the stable window before the power-on pulse is applied. This represents the first pulse current value, which is also the average battery current of the battery pack under test within a short time window after the power-on pulse is established. This represents the second pulse current value, which is also the pulse current value of the battery pack under test within the stable window before the power-on pulse is applied.

[0054] The power-on pulse estimates the ohmic internal resistance by utilizing the current step that naturally occurs during normal vehicle operation, without the need for a dedicated test pulse or additional hardware. Naturally occurring current steps include the establishment of the pre-charge current when the vehicle is powered on and woken up, the load step when a DC / DC converter starts, and the sudden current change when a high-voltage air conditioning compressor or heater starts.

[0055] When a current step event is detected, the battery voltage and current data before and after the pulse are recorded. The ohmic internal resistance is determined based on the changes in battery voltage and current before and after the pulse.

[0056] The advantage of power-on pulses lies in their ability to track internal resistance online using natural operating conditions, without interrupting normal battery operation or requiring additional specialized testing equipment. Since the battery pack under test is installed in the vehicle, the accumulated usage time of the vehicle results in a time series of internal resistance changes through multiple power-on pulse measurements. This allows for tracking the aging trend of the battery's internal resistance and provides data support for SOH estimation.

[0057] It should be noted that, Figure 3 This is just one example of a power-on pulse; power-on pulses are not limited to this one pulse curve.

[0058] S1014. Compensate the real-time ohmic internal resistance based on the battery temperature, state of charge, and battery health status to obtain the compensated ohmic internal resistance.

[0059] In this embodiment, different battery temperatures are determined by the power-on pulse method or online identification method. The original ohmic resistance under different SOC conditions and different SOH conditions Establish the mapping relationship between the above three parameters, and then form a temperature compensation model. , This represents the compensated ohmic resistance. This indicates the battery temperature, SOC, SOH, and initial ohmic internal resistance. The mapping relationship between them is then established. Based on the Arrhenius equation or a lookup table, the real-time battery temperature and the compensated ohmic resistance corresponding to the State of Charge (SOC) are determined. By compensating for the real-time ohmic resistance, the consistency of the corrected voltage calculation under different battery temperatures and SOC conditions is ensured.

[0060] It should be noted that battery temperature can be the cell temperature corresponding to the lowest individual cell voltage, the lowest battery temperature of the entire battery pack module, or the lowest temperature of the battery pack.

[0061] S1015. Construct an equivalent circuit model and use the equivalent circuit model to determine the real-time polarization voltage of the battery pack under test.

[0062] In this embodiment, the polarization voltage is recursively determined using a first-order or multi-order resistor-capacitor equivalent circuit model. Taking the recursive determination of the polarization voltage using a first-order capacitor equivalent circuit model as an example, the polarization voltage is: ; in, Indicates the first The polarization voltage at any given moment is also the polarization voltage of the current cycle; Indicates the first The polarization voltage at any given moment is also the polarization voltage of the previous cycle; Indicates the attenuation coefficient; Indicates polarization resistance; Indicates the first Battery current at any given moment.

[0063] parameter and parameters All parameters can be determined offline. For example, under standard temperature conditions (25°C), a pulse current is applied to the cell, and the voltage response curve is fitted to obtain the parameters. and parameters Typical values.

[0064] Understandably, the equivalent circuit model is also used to determine the polarization voltage of the battery pack under test at future times.

[0065] S1016. Based on the polarization voltage, battery current, and compensated ohmic internal resistance, the lowest single-cell voltage is corrected under load to obtain the corrected voltage. Specifically: ; in, Indicates the corrected voltage; Indicates the minimum voltage of a single battery cell; This represents the battery current, which is also the discharge current during the discharge process of the battery pack under test. This represents the compensated ohmic resistance; This represents the polarization voltage.

[0066] Minimum single cell voltage Ohmic voltage drop term in and polarization voltage The corrected voltage is obtained after decomposition and compensation. It more closely approximates the open-circuit voltage characteristic. Combined with Figure 2 It can be seen that the original single-cell voltage is also the lowest single-cell cell voltage. The corrected voltage is obtained due to significant fluctuations caused by changes in load current. After compensation, it exhibits a smooth downward trend, with obvious slope change characteristics at the end of the plateau region, providing a clear data foundation for subsequent slope identification.

[0067] In this embodiment of the application, step S102 specifically includes: S1021. Place each sample battery with different model information and different SOH under various ambient temperatures, and perform constant current discharge on each sample battery with an initial state of charge of 100% at different discharge rates, and determine the battery voltage and actual usable capacity of each sample battery at each time point during the discharge process.

[0068] The offline calibration process can perform constant current discharge at different current rates on battery packs with different lifespan states (such as 100% SOH, 80% SOH, 70% SOH, 60% SOH, etc.) under different ambient temperatures (such as 45℃, 25℃, 10℃, 0℃, -10℃, -15℃, -25℃, etc.) until the cutoff voltage of 2.0V is reached. The charge / discharge machine records data such as time, battery voltage and actual usable capacity during the entire discharge process.

[0069] Since the discharge performance of battery packs varies at different State of Emergency (SOH), in order to better simulate the discharge process of various battery packs and obtain more reliable and complete discharge data, sample batteries with the same model information at each SOH will be selected for testing. By increasing the amount of sample data, the entire life cycle of the sample battery, various discharge rates, and the temperature range of various driving environments of the vehicle will be covered.

[0070] In this embodiment, each sample battery can be first charged to its full charge voltage, which is the battery voltage corresponding to a 100% State of Charge (SOC). This ensures that each sample battery is fully charged before constant current discharge. The sample batteries are then placed in different test environments and discharged from their full charge voltage to a cutoff voltage (e.g., 2V) using different discharge rates. Data such as the time, battery voltage, and actual usable capacity of each sample battery during the complete discharge process under different test environments are recorded.

[0071] It should be noted that the discharge rate is a low-rate discharge, for example, a discharge rate between 0.05C and 0.2C.

[0072] S1022. Based on the battery voltage and actual usable capacity, establish the battery voltage-capacity discharge curves for each sample battery at the corresponding ambient temperature and discharge rate.

[0073] S1023. Perform piecewise fitting and differential analysis on the battery voltage-capacity discharge curve, dividing the battery voltage-capacity discharge curve into a plateau region and a terminal voltage drop region.

[0074] Within the plateau region, the rate of change of voltage with capacity is extremely small (close to zero), while within the terminal voltage drop region, the rate of change of voltage with capacity increases significantly. By using piecewise linear fitting or curve fitting methods, the plateau region, the terminal voltage drop region, and the transition point between the plateau region and the terminal voltage drop region, i.e., the critical point, can be determined. This critical point is also the subsequent reference inflection point.

[0075] It should be noted that the end voltage drop zone is located at the rear end of the plateau zone, which is the discharge period when the battery pack leaves the plateau zone. At the front end of the plateau zone, there is also an initial discharge zone, which is the discharge period when the battery pack has not yet entered the plateau zone.

[0076] S1024. The critical point between the platform region and the end voltage drop region is taken as the reference inflection point of the sample battery under the corresponding ambient temperature and discharge rate, and the slope of the reference inflection point is taken as the reference inflection point threshold.

[0077] Specifically, the reference inflection point threshold is: ; in, Indicates the reference inflection point threshold. The unit is V / Ah; Indicates the discharge voltage; This indicates the cumulative discharge capacity.

[0078] The reference inflection point threshold is extracted by taking the derivative.

[0079] The specific value of the reference inflection point threshold is obtained by dividing the battery voltage at the time node corresponding to the critical point by the actual available capacity at the corresponding time node. The unit of the reference inflection point threshold is V / Ah.

[0080] S1025. Establish a mapping relationship between model information, SOH, ambient temperature, discharge rate, and reference inflection point threshold. This mapping relationship can be expressed as: ; in, This indicates the mapping relationship between model information, SOH, ambient temperature, discharge rate, and reference inflection point threshold. Indicates the battery model; Indicates ambient temperature; Indicates the battery's health status; This indicates the discharge rate.

[0081] Based on the mapping relationship, an offline table can be established. For example, for a typical lithium iron phosphate cell, under conditions of 25℃, 100% SOH, and 0.2C, a reference inflection point threshold can be set. The value is 0.03V / Ah. This reference inflection point threshold represents the electrochemical transition characteristics of this battery pack model under no-load or near-no-load conditions, serving as a benchmark reference for online identification.

[0082] S1026. Extract the reference inflection point threshold of the battery pack to be detected based on the mapping relationship.

[0083] Through the above offline calibration, a database of reference inflection point thresholds reflecting the intrinsic electrochemical characteristics of the battery was established. This database can be used throughout the entire life cycle of the battery pack. When battery aging causes changes in SOH, the corresponding reference inflection point threshold can be obtained by querying or interpolating from the database using online estimated SOH values.

[0084] In this embodiment of the application, step S103 specifically includes: S1031. Determine the cumulative value of the cumulative discharge capacity within each sliding window.

[0085] Slope recognition is performed on a sliding window. The duration of the sliding window is determined by a combination of the cell capacity of the battery pack being tested and the required accuracy.

[0086] Considering that a sliding window duration that is too short would make the slope calculation overly sensitive to noise, resulting in unstable recognition results, while a sliding window duration that is too long would lead to delays in inflection point recognition, reducing the timeliness of protection, in this embodiment, the sliding window duration is 2% to 5% of the rated capacity, thus achieving a good balance between noise suppression and response speed.

[0087] S1032. If the cumulative value does not exceed the preset capacity, the slope of the corrected voltage relative to the cumulative discharge capacity at each time node within the sliding window is determined by differentiation, and the slope of the corrected voltage at each time node is obtained.

[0088] In this embodiment, the time window assists in slope identification. If sufficient capacity change is not accumulated within the sliding window, i.e., the accumulated value is lower than the preset capacity (e.g., the vehicle is in low-power cruising condition), the corrected voltage slope at each time point is calculated by differentiation. Specifically: ; in, Indicates the corrected voltage slope; Indicates cumulative discharge capacity, parameter It can be calculated in real time using ampere-hour integration, or indirectly based on SOC.

[0089] By using differentiation, we can ensure that the corrected voltage slope can be obtained even under long-term operation with low current, avoiding the inability to obtain the corrected voltage slope simply by using the changes in the starting and ending points of the sliding window.

[0090] S1033. When the cumulative value exceeds the preset capacity, determine the slope of the correction voltage relative to the cumulative discharge capacity at the start and end points of the sliding window, and obtain the correction voltage slope corresponding to the sliding window. Specifically: ; in, This indicates the correction value for the voltage change within the sliding window; This represents the cumulative change in discharge capacity within the sliding window; This represents the correction voltage corresponding to the end point of the sliding window; This indicates the correction voltage corresponding to the starting point of the sliding window; This indicates the cumulative discharge capacity corresponding to the end point of the sliding window; This represents the cumulative discharge capacity corresponding to the starting point of the sliding window.

[0091] Please see Figure 4 , Figure 4 The yellow area in the middle is the judgment interval at the end of the platform area. Under most operating conditions, the cumulative value determined within the sliding window will exceed the preset capacity. Accordingly, the slope of the corrected voltage determined by the difference method does not depend on the voltage jump of a single data point, but calculates the overall trend of the corrected voltage relative to the cumulative discharge capacity within the entire window.

[0092] Each time the sliding window is updated, it slides forward and the corrected voltage slope is recalculated.

[0093] S1034. If the corrected voltage slope within a predetermined number of consecutive sliding windows is not lower than the reference inflection point threshold, determine that the battery pack to be tested has entered the final judgment interval of the platform area.

[0094] Set the counter and preset quantity M; for example, M can be set to three. The voltage slope will be corrected after each sliding window update. Compared with the reference inflection point threshold The counter is incremented by one if the corrected voltage slope is determined to be no lower than the reference inflection point threshold, and reset to zero if the corrected voltage slope is determined to be lower than the reference inflection point threshold. Only when the counter count reaches M is the battery pack under test determined to have entered the final judgment interval of the platform area.

[0095] By using a sliding window slope calculation and continuous confirmation mechanism, a stable and reliable corrected voltage slope is extracted from the noise-contaminated corrected voltage signal, effectively distinguishing between real electrochemical state transitions and transient disturbances, and improving the accuracy and robustness of plateau region inflection point identification.

[0096] In this embodiment of the application, step S104 specifically includes: S1041. Determine the vehicle's load power supply information and construct a future requested current trajectory based on the load power supply information. .

[0097] Please see Figure 5 , Figure 5The lower half is a magnified schematic diagram of the upper half after being enlarged to 0-1s. In the embodiments of this application, the future requested current trajectory (sequence) is constructed based on the following information: the current vehicle power request (from the vehicle controller or driver input), DC / DC converter load, thermal management load, drive load, historical power change rate, conservative margin, and safety conservative strategy to construct the future requested current trajectory.

[0098] For example, if the vehicle is currently parked for a short period, and the driver has turned on the air conditioning and controlled the in-vehicle media entertainment system to play music, but the DC / DC converter is not supplying power, the SOC of the battery pack under test is low. Based on this information, a future requested current trajectory will be constructed. According to this constructed future requested current trajectory, the BMS needs to ensure that a certain SOC is reserved even when continuously using the battery pack under test for power. Accordingly, the main relay needs to be disconnected in advance. The reserved SOC is used to ensure that the battery pack under test will not be over-discharged in the event of a long-term parking period (e.g., 8 months). This reserved SOC ensures the safe use of the battery.

[0099] For example, if the vehicle is currently parked for an extended period, the constructed future requested current trajectory only reflects the vehicle's static operating conditions (including dormant current information for multiple automotive electronic control units). Based on this trajectory, the BMS needs to ensure that a certain state of charge (SOC) is reserved even when continuously powered by the battery pack under test. Accordingly, the main relay needs to be disconnected in advance. This reserved SOC ensures that the battery pack under test will not be over-discharged during extended periods of parking (e.g., 8 months), guaranteeing safe battery operation.

[0100] Future request current trajectory It can also be expressed as: , , This represents a discrete time interval. Assume a prediction time window. Set to 180s so that future requests for current traces will be processed. It will cover the current moment To the future The interval, and within that interval, the prediction time window Discretize into N Interval.

[0101] S1042. Schedule the SOC at a future time according to the future requested current trajectory, and determine the open-circuit voltage at a future time based on the battery temperature, SOH and the SOC at a future time.

[0102] In this application embodiment, the future requested current trajectory Each time point has a corresponding battery current, based on the future requested current trajectory. The battery current at each time point can be constructed Time to The current curve at a given time can be used to obtain the trajectory of the future requested current through the ampere-hour integration method. The SOC consumed at each time point, or in other words, each The SOC consumed within the interval is subtracted from the consumed SOC in the current SOC to determine the future SOC, i.e., the scheduling parameters. The specific value.

[0103] Understandably, this is in conjunction with the future requested current trajectory. Real-time SOC can also be determined using methods such as the open-circuit voltage method and Kalman filtering based on the equivalent circuit model. The specific value.

[0104] In this embodiment of the application, the open-circuit voltage at future times is determined by using a pre-constructed OCV-SOC-T-SOH curve and the obtained real-time SOC, battery temperature and SOH.

[0105] The OCV-SOC-T-SOH curve is constructed based on offline testing of sample batteries of the same model as the battery pack under test but belonging to different battery aging stages (using SOH to reflect the aging stage). In the offline testing stage, the OCV corresponding to each actual SOC of the sample battery during the discharge process is obtained, and the OCV-SOC curve is determined based on the SOC and its corresponding OCV.

[0106] Since the OCV of the battery pack is affected by the battery temperature, the sample battery is repeatedly subjected to offline testing at different test temperatures, thereby obtaining the OCV-SOC-T curves at different test temperatures.

[0107] Since the selected sample batteries included different battery aging stages, the OCV-SOC-T curves of different battery aging stages were summarized, and finally the OCV-SOC-T-SOH curves were obtained.

[0108] For each offline test at each test temperature, the sample battery is allowed to rest for a preset time to ensure it reaches a stable internal state. Then, a preset constant charging current is used to charge the sample battery. When the sample battery is nearly fully charged (e.g., 90% SOC), a preset constant charging voltage is used to charge it until it reaches a preset current state. The preset current state is defined as the battery current dropping to a certain threshold to ensure the battery pack is fully charged. Next, a preset constant discharge current is used to discharge the sample battery at the preset current state, and the OCV corresponding to each actual SOC during the discharge process is obtained until the battery discharge is complete.

[0109] That is, scheduling first Then by Get parameters .

[0110] S1043. Construct an equivalent circuit model and use the equivalent circuit model to determine the polarization voltage of the battery pack under test at future times. See step S1015 for details.

[0111] S1044. Based on the future requested current trajectory, battery temperature, battery health status, compensated ohmic resistance, future polarization voltage, and future open-circuit voltage, predict the future state of charge (SOC) at the time when the terminal voltage reaches the sum of the undervoltage protection threshold and the safety margin threshold, and determine the corresponding future SOC as the actual operating inflection point. .

[0112] Essentially, it means predicting how much the future SOC of the battery pack under test will need to be reduced to meet the requirements. .

[0113] The method may also include: S201. Obtain the real-time operating status of the battery pack to be tested, determine the lowest single cell voltage based on the real-time operating status, and perform load correction on the lowest single cell voltage based on the real-time operating status to obtain the corrected voltage.

[0114] S202. The reference inflection point threshold of the battery pack under test is calibrated offline.

[0115] S203. Determine the slope of the correction voltage relative to the cumulative discharge capacity within the preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be tested has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold.

[0116] S204 is used to construct the future requested current trajectory, predict the terminal voltage at future times based on the future requested current trajectory, and determine the actual operating inflection point based on the terminal voltage at future times.

[0117] S205. Determine the energy retention threshold based on the product of the critical load maintenance power and the target maintenance time. Take the larger value between the actual operating inflection point and the energy retention threshold as the comprehensive protection boundary. Triage undervoltage protection is triggered based on the comprehensive protection boundary and the actual operating inflection point.

[0118] After obtaining the actual operating inflection point of the vehicle under the current operating conditions, the energy retention threshold is first determined based on the critical load maintenance power and the target maintenance time. Then, the larger value between the actual operating inflection point and the energy retention threshold is taken as the comprehensive protection boundary. The comprehensive protection boundary is used to ensure that when the battery is close to the end of the discharge, there is always enough energy to maintain the critical load for a specified time, so as to avoid the critical system losing power due to over-discharge.

[0119] By taking the maximum value, the integrated protection boundary simultaneously satisfies both electrochemical and functional safety constraints. When either constraint is more stringent, the integrated protection boundary automatically adopts the more conservative constraint, thereby ensuring system safety.

[0120] When the real-time estimated state of charge (SOC) is less than or equal to the sum of the integrated protection boundary and the SOC margin, graded undervoltage protection is triggered. The safety margin provides an additional safety buffer for the integrated protection boundary, covering the uncertainty of SOC estimation errors and sudden changes in operating conditions.

[0121] Specifically, step S205 includes: S2051. The product of the total sustaining power of the critical load and the target sustaining time is taken as the energy that needs to be retained from the battery pack under test, thus obtaining the energy retention threshold, i.e.: ; in, Indicates the energy retention threshold; This indicates the total sustaining power of the critical load; Indicates the duration of the target; It is a unit of capacity.

[0122] Critical load sustaining power Duration of the target The power required is determined by the user's actual application needs. For example, suppose a safety controller needs 50W of power to maintain operation for 10 minutes, emergency lighting needs 20W of power to maintain operation for 30 minutes, and critical loads need to maintain their power. The target duration is the sum of the power of all critical loads. This represents the maximum of the required sustain time for each critical load.

[0123] S2052. Take the larger value between the actual operating inflection point and the energy retention threshold as the comprehensive protection boundary, that is: ; in, Indicates the comprehensive protection boundary; This indicates the actual inflection point in operation.

[0124] S2053. Triage undervoltage protection is triggered based on the comprehensive protection boundary and the actual operating inflection point.

[0125] Specifically, the graded undervoltage protection adopts the following method: Normal operating state S0: When the corrected voltage slope is determined to be less than the reference inflection point threshold, the system enters normal operating state S0, indicating that the battery pack under test has not yet approached the actual operating inflection point and the voltage margin is sufficient. Under this normal operating state S0, the BMS can control the battery pack under test to discharge normally without the need for protection intervention. This has no impact on the user and will not affect the user's operation of various vehicle functions.

[0126] Platform end observation state S1: Within a predetermined number of consecutive sliding windows, the corrected voltage slope is not lower than the reference inflection point threshold, and the voltage safety margin is... Still relatively sufficient (e.g.) , (Indicates a sufficiency threshold, for example, 150mV), and accordingly enters the platform end observation state. In this platform end observation state S1, the BMS increases the monitoring and calculation frequency (for example, increasing the sampling rate of relevant data from the normal frequency to 2 or 4 times), enhancing the ability to track voltage drop trends, but does not perform power limiting.

[0127] In this application embodiment, in addition to determining the comprehensive protection boundary In addition, a voltage safety margin is introduced. and its rate of change Monitoring to provide an additional dimension of early warning. Voltage safety margin. The rate of change reflects how quickly the battery voltage approaches the undervoltage boundary. Wherein: ; Voltage safety margin The monitoring and integrated protection boundary complement each other. The integrated protection boundary provides a protection boundary based on SOC, suitable for judging the actual safety margin and its rate of change under steady-state conditions. The monitoring of voltage drop trends provides early warning and is suitable for rapid response under dynamic conditions. When either one triggers the protection condition, the state machine executes the corresponding protection action.

[0128] It should be noted that when in the platform end observation state S1, if the corrected voltage slope within a certain number of consecutive preset sliding windows is lower than the reference inflection point threshold, it indicates that the battery's downward trend remains stable, and the platform end observation state S1 can be switched to the normal operation state S0.

[0129] Low Battery Warning State S2: When the corrected voltage slope drops to the actual operating inflection point, the low battery warning state is entered. Under this low battery warning state S2, the BMS sends a low battery warning signal to the vehicle controller to notify the driver that the battery is about to run out of power.

[0130] Power limiting state S3: When the voltage safety margin is... Rapid decline, that is When the rate of decline exceeds a threshold, such as 1 mV / s, it indicates that the undervoltage risk of the battery pack under test is rapidly increasing. In this power-limiting state S3, the BMS limits drive power, thermal management power, and accessory power, reducing the discharge current to decrease the load voltage drop at the terminals and prevent the voltage from rapidly approaching the undervoltage boundary. The power-limiting strategy can be gradual, first limiting the power of non-critical accessories, then limiting the thermal management power, and finally limiting the drive power.

[0131] It should be noted that when in low battery warning state S2, when the voltage safety margin... Rapid decline, that is When the rate of decrease exceeds a threshold, such as 1mV / s, the low battery warning state S2 can be switched to the power limiting state S3; when in the power limiting state S3, when When the vehicle is in a charging state, the power state S3 can be switched to the platform end observation state S1 or the normal operation state S0.

[0132] Reserved Operation State S4: When the real-time SOC (State of Charge), i.e., the remaining SOC of the battery pack under test, is determined to be no more than the sum of the comprehensive protection boundary and the SOC margin, the system enters Reserved Operation State S4. In Reserved Operation State S4, the BMS shuts down all non-critical loads, maintaining power supply only to critical loads (battery management system, safety controller, emergency lighting, communication modules, etc.) to ensure that critical loads maintain power. Able to maintain the target duration During operation, the discharge current in the retained operating state is significantly reduced, the terminal voltage rises accordingly, and the availability time of critical functions is extended.

[0133] If the remaining SOC exceeds the sum of the comprehensive protection boundary and the SOC margin, it indicates that the battery pack under test has entered the charging state. It can switch from the reserved operation state S4 to the power limiting state S3, and gradually switch to the low power warning state S2, the platform end observation state S1, and finally the normal operation state S0 during the charging process.

[0134] Controlled power-down state S5: After determining the voltage safety margin ≤ If the real-time SOC is lower than the SOC reservation threshold (i.e., the remaining SOC of the battery pack under test is insufficient to maintain the minimum operating requirements of the critical load), the system enters controlled power-down state S5. This indicates a safety margin threshold. In this controlled power-down state S5, the BMS performs an orderly power-down operation: saving critical data (fault codes, status information, cycle counts, etc.), notifying the vehicle controller to prepare for power-down, disconnecting relays in a preset sequence (first the main positive relay, then the main negative relay), and entering sleep mode. Controlled power-down avoids uncontrolled power outages caused by sudden undervoltage, protecting the data integrity and hardware safety of the battery management system.

[0135] By dividing the protection process at the end of the battery platform area into five stages—observation, early warning, power limiting, sustained operation, and controlled power-off—each stage has a clear physical meaning and judgment criteria, ensuring the maintenance of critical safety and communication functions. Simultaneously, the transitions between states are based on a comprehensive judgment of multiple characteristic quantities, rather than a single fixed threshold. This progressive protection strategy minimizes the impact on users. The following description of the battery platform area end identification device provided by this invention is relevant to the battery platform area end identification method described above.

[0136] To address the aforementioned issues, this specification provides a device for identifying the end of the battery plateau region, which aims to achieve accurate online identification of the actual inflection point at the end of the battery pack discharge process under load, aging, and variable temperature conditions. Figure 6 This is a schematic diagram of the structure of the identification device at the end of the battery platform area according to an embodiment of the present invention, as shown below. Figure 6 As shown, the device may include: The load correction module 10 is used to acquire the real-time operating status of the battery pack under test, determine the minimum single-cell voltage based on the real-time operating status, and perform load correction on the minimum single-cell voltage based on the real-time operating status to obtain the corrected voltage. The real-time operating status includes real-time battery voltage, battery current, battery temperature, state of charge, and battery health status.

[0137] The offline calibration module 20 is used to calibrate the reference inflection point threshold of the battery pack under test offline.

[0138] The interval identification module 30 is used to determine the slope of the corrected voltage relative to the cumulative discharge capacity within a preset sliding window, obtain the corrected voltage slope corresponding to each sliding window, and determine whether the battery pack to be detected has entered the end judgment interval of the platform area based on the corrected voltage slope and the reference inflection point threshold.

[0139] The inflection point identification module 40 is used to construct the future requested current trajectory, predict the terminal voltage at future times based on the future requested current trajectory, and determine the actual operating inflection point based on the terminal voltage at future times.

[0140] The battery platform region end identification device of the present invention determines the lowest single cell voltage based on the real-time operating status, and performs load correction on the lowest single cell voltage based on the real-time operating status to obtain a corrected voltage. Then, it extracts the corrected voltage slope reflecting the actual electrochemical state change from the terminal voltage affected by the coupling of load, aging and temperature factors. The corrected voltage slope is then compared with the reference inflection point threshold of the battery pack under test through offline calibration, thereby distinguishing between load voltage drop and the actual SOC end voltage drop. Furthermore, future load changes are incorporated into the inflection point determination through forward voltage prediction, so that the protection strategy matches the actual operating conditions. This achieves online accurate identification of the actual inflection point at the end of the battery pack discharge process platform region under load, aging and variable temperature conditions, and solves the problem that the fixed threshold method cannot adapt to changes in actual operating conditions.

[0141] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 7 As shown, the electronic device may include a processor 710, a communication interface 720, a memory 730, and a communication bus 740. The processor 710, communication interface 720, and memory 730 communicate with each other via the communication bus 740. The processor 710 can call logical commands stored in the memory 730 to execute the identification method at the end of the battery platform area.

[0142] Furthermore, the logical instructions in the aforementioned memory 730 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0143] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the battery platform region end identification method provided by the above methods.

[0144] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the aforementioned methods for identifying the end of the battery platform region.

[0145] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. 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 any creative effort.

[0146] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying the end of a battery platform region, characterized in that, The method includes: The system acquires the real-time operating status of the battery pack under test, determines the minimum single-cell voltage based on the real-time operating status, and performs load correction on the minimum single-cell voltage based on the real-time operating status to obtain the corrected voltage. The real-time operating status includes real-time battery voltage, battery current, battery temperature, state of charge, and battery health status. The reference inflection point threshold of the battery pack under test is calibrated offline. Determine the slope of the correction voltage relative to the cumulative discharge capacity within the preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be tested has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold. Once the platform area is determined to be the end judgment interval, the load power supply information of the vehicle is determined, and the future request current trajectory is constructed based on the load power supply information. The terminal voltage at the future time is predicted based on the future request current trajectory, and the state of charge at the future time is predicted when the terminal voltage at the future time reaches the sum of the preset undervoltage protection threshold and the safety margin threshold. The state of charge at the corresponding future time is determined as the actual operating inflection point. The process of acquiring the real-time operating status of the battery pack under test, determining the lowest single-cell voltage based on the real-time operating status, and performing load correction on the lowest single-cell voltage based on the real-time operating status to obtain the corrected voltage specifically includes: Obtain the real-time operating status of the battery pack under test; The lowest real-time cell voltage of the battery pack under test is determined based on the real-time battery voltage. Based on the power-on pulse during vehicle startup, the battery voltage and current are processed to extract the real-time internal resistance of the battery pack under test. The real-time ohmic internal resistance is compensated based on battery temperature, state of charge, and battery health status to obtain the compensated ohmic internal resistance. Construct an equivalent circuit model and use the equivalent circuit model to determine the real-time polarization voltage of the battery pack under test; The lowest single-cell voltage is corrected by load adjustment based on polarization voltage, battery current, and compensated ohmic internal resistance to obtain the corrected voltage.

2. The method for identifying the end of the battery platform region according to claim 1, characterized in that, The offline calibration of the reference inflection point threshold of the battery pack under test specifically includes: Each sample battery with different model information and different battery health status was placed under various ambient temperatures and constant current discharge was performed on each sample battery with an initial state of charge of 100% at different discharge rates. The battery voltage and actual usable capacity of each sample battery at each time point during the discharge process were determined. Based on the battery voltage and actual usable capacity, establish the battery voltage-capacity discharge curves of each sample battery at the corresponding ambient temperature and discharge rate. Piecewise fitting and differential analysis were performed on the battery voltage-capacity discharge curve, dividing the battery voltage-capacity discharge curve into a plateau region and a terminal voltage drop region. The critical point between the platform region and the end voltage drop region is used as the reference inflection point of the sample battery under the corresponding ambient temperature and discharge rate, and the slope of the reference inflection point is used as the reference inflection point threshold. Establish a mapping relationship between model information, battery health status, ambient temperature, discharge rate and reference inflection point threshold; The reference inflection point threshold of the battery pack to be detected is extracted based on the mapping relationship.

3. The method for identifying the end of the battery platform region according to claim 1, characterized in that, The process involves determining the slope of the corrected voltage relative to the cumulative discharge capacity within a preset sliding window, obtaining the corrected voltage slope corresponding to each sliding window, and determining whether the battery pack to be tested has entered the end judgment interval of the plateau region based on the corrected voltage slope and a reference inflection point threshold. Specifically, this includes: Determine the cumulative value of the cumulative discharge capacity within each sliding window; If the cumulative value does not exceed the preset capacity, the slope of the corrected voltage relative to the cumulative discharge capacity at each time point within the sliding window is determined by taking the derivative, and the slope of the corrected voltage at each time point is obtained. If the cumulative value exceeds the preset capacity, determine the slope of the correction voltage relative to the cumulative discharge capacity at the start and end points of the sliding window, and obtain the correction voltage slope corresponding to the sliding window. If the corrected voltage slope within a predetermined number of consecutive sliding windows is not lower than the reference inflection point threshold, the battery pack to be tested is determined to enter the final judgment interval of the platform area.

4. The method for identifying the end of the battery platform region according to claim 2, characterized in that, In the case of determining the end judgment interval of entering the platform area, the load power supply information of the vehicle is determined, and a future requested current trajectory is constructed based on the load power supply information. The terminal voltage at a future time is predicted based on the future requested current trajectory, and the state of charge at the corresponding future time when the terminal voltage at the future time reaches the sum of the preset undervoltage protection threshold and the safety margin threshold is predicted. The corresponding state of charge at the future time is determined as the actual operating inflection point, specifically including: The state of charge at future times is scheduled based on the future requested current trajectory, and the open-circuit voltage at future times is determined based on battery temperature, battery health status, and the state of charge at future times. Construct an equivalent circuit model and use the equivalent circuit model to determine the polarization voltage of the battery pack under test at future times; Based on the future requested current trajectory, battery temperature, battery health status, compensated ohmic resistance, future polarization voltage, and future open-circuit voltage, predict the state of charge at the future time when the terminal voltage reaches the sum of the undervoltage protection threshold and the safety margin threshold, and determine the corresponding future state of charge as the actual operating inflection point.

5. The method for identifying the end of the battery platform region according to claim 4, characterized in that, The formula for calculating the terminal voltage at the future time is: ； ； in, Indicates the first Terminal voltage at time , Indicates the time-domain variable for prediction. , Indicates the forecast time window; This indicates that based on battery temperature, battery health status, and the first The open-circuit voltage predicted by the state of charge at time t. , Indicates the first State of charge at time t, Indicates battery temperature; Indicates the first The battery current at a given moment can be used to determine the battery current corresponding to each future moment in the trajectory based on the future requested current trajectory. This represents the compensated ohmic resistance; Indicates the first Polarization voltage at time; Indicates the undervoltage protection threshold; This indicates the safety margin threshold.

6. The method for identifying the end of the battery platform region according to claim 1, characterized in that, The method further includes: The energy retention threshold is determined by the product of the critical load sustaining power and the target sustaining time. The larger value between the actual operating inflection point and the energy retention threshold is taken as the comprehensive protection boundary. The graded undervoltage protection is triggered based on the comprehensive protection boundary and the actual operating inflection point.

7. An identification device for the end of a battery platform region, characterized in that, The device includes: The load correction module is used to acquire the real-time operating status of the battery pack under test, determine the minimum single cell voltage based on the real-time operating status, and perform load correction on the minimum single cell voltage based on the real-time operating status to obtain the corrected voltage; the real-time operating status includes real-time battery voltage, battery current, battery temperature, state of charge, and battery health status. The offline calibration module is used to calibrate the reference inflection point threshold of the battery pack under test offline. The interval identification module is used to determine the slope of the correction voltage relative to the cumulative discharge capacity within a preset sliding window, obtain the correction voltage slope corresponding to each sliding window, and determine whether the battery pack to be detected has entered the end judgment interval of the platform area based on the correction voltage slope and the reference inflection point threshold. The inflection point identification module is used to determine the load power supply information of the vehicle when it is determined to enter the end judgment interval of the platform area, and construct the future request current trajectory based on the load power supply information. It predicts the terminal voltage at the future time based on the future request current trajectory, and predicts the state of charge at the future time when the terminal voltage at the future time reaches the sum of the preset undervoltage protection threshold and the safety margin threshold. It then determines the state of charge at the corresponding future time as the actual operating inflection point. The process of acquiring the real-time operating status of the battery pack under test, determining the lowest single-cell voltage based on the real-time operating status, and performing load correction on the lowest single-cell voltage based on the real-time operating status to obtain the corrected voltage specifically includes: Obtain the real-time operating status of the battery pack under test; The lowest real-time cell voltage of the battery pack under test is determined based on the real-time battery voltage. Based on the power-on pulse during vehicle startup, the battery voltage and current are processed to extract the real-time internal resistance of the battery pack under test. The real-time ohmic internal resistance is compensated based on battery temperature, state of charge, and battery health status to obtain the compensated ohmic internal resistance. Construct an equivalent circuit model and use the equivalent circuit model to determine the real-time polarization voltage of the battery pack under test; The lowest single-cell voltage is corrected by load adjustment based on polarization voltage, battery current, and compensated ohmic internal resistance to obtain the corrected voltage.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for identifying the end of the battery platform region as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for identifying the end of the battery platform region as described in any one of claims 1 to 6.

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