Electric vehicle power battery soe smoothing correction method and system and electric vehicle

Abstract

The present application belongs to the field of electric vehicle power battery management, and provides an electric vehicle power battery SOE smoothing correction method, system and electric vehicle, comprising: when the vehicle is powered on, the current cell temperature and the corresponding target capacity retention rate of the power battery are obtained; based on the size relationship between the current cell temperature of the power battery and the cell temperature when the vehicle is powered off last time, the corresponding capacity retention rate smoothing correction strategy is determined to obtain the corrected capacity retention rate; the real state of charge of the power battery is calculated according to the corrected capacity retention rate, and is sent to the vehicle instrument display. Through the technical scheme provided by the present application, based on the two-dimensional judgment of the temperature change direction and the charging and discharging working condition, the differentiated smoothing correction strategy is adopted to avoid the problem of instrument SOC sudden drop or rapid zero caused by the sudden change of capacity retention rate, realize SOE smoothing correction, and improve the user experience.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle power battery management technology, specifically relating to an electric vehicle power battery SOE smoothing correction method, system, and electric vehicle. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Electric vehicle power batteries face challenges such as limited charging power and reduced energy output under low-temperature conditions, leading to a significant decrease in remaining usable energy. Current low-temperature discharge conditions typically employ the following SOE (State of Energy) management strategy for power batteries: Based on the cell temperature, SOC (State of Charge), and remaining usable energy detected when the vehicle is powered off, these are stored; upon power-up, the remaining usable energy and frozen energy at the current temperature are retrieved from a table. During discharge, when the true SOC (at low temperatures) drops to 0 and is less than the following SOC, the following SOC approaches the true SOC at a certain rate.

[0004] However, when an electric vehicle is cold-started after being left to stand overnight in a low-temperature environment, this strategy can cause the SOC displayed on the instrument panel to jump rapidly to 0, which can easily cause user panic and seriously affect the user experience. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a method, system, and electric vehicle for smoothing SOE (State of Energy) correction of electric vehicle power batteries. Based on a dual-dimensional judgment of temperature change direction and charging / discharging conditions, this invention performs differentiated smoothing correction of capacity retention rate, avoiding abrupt changes in SOE / SOC display and effectively solving the problem of rapid SOC drop to zero on the instrument panel after cold starts in extremely low-temperature environments, significantly improving the user experience. It rapidly releases frozen capacity as the temperature rises, enhancing the perceived vehicle range; maintains a constant capacity retention rate during charging as the temperature drops, avoiding abnormal fluctuations in SOC display; and slowly adjusts the capacity retention rate during discharging as the temperature drops, accurately reflecting changes in available battery energy. Employing ampere-hour integral quantity to identify charging / discharging conditions effectively avoids misjudgments caused by instantaneous current fluctuations, improving system stability and reliability. This invention solves the problems of abrupt SOC display due to sudden temperature changes caused by static lookup table methods, rapid SOC drop to zero on the instrument panel after cold starts in extremely low-temperature environments causing user panic due to the SOC following SOC scheme, and unsmooth SOE / SOC display due to the lack of differentiated processing of charging / discharging conditions in existing technologies.

[0006] According to some embodiments, the first aspect of the present invention provides a method for smoothing SOE correction of electric vehicle power batteries, which adopts the following technical solution: A method for smoothing SOE in electric vehicle power batteries, applied to the battery management system of electric vehicles, includes: When the vehicle is powered on, the current cell temperature and the corresponding target capacity retention rate of the power battery are obtained according to the preset relationship between cell temperature and target capacity retention rate. Based on the relationship between the current cell temperature and the cell temperature at the last power-off time, a corresponding capacity retention rate smoothing correction strategy is determined to obtain the corrected capacity retention rate. The true state of charge of the power battery is calculated based on the corrected capacity retention rate and sent to the vehicle's instrument panel display.

[0007] In some embodiments, based on the relationship between the current cell temperature and the cell temperature at the time of the last power-off, a corresponding capacity retention smoothing correction strategy is determined to obtain the corrected capacity retention rate, including: If the current cell temperature of the power battery is lower than the cell temperature when it was last powered off, the current capacity retention rate under the charging and discharging conditions is determined based on the cumulative ampere-hour integral amount within a set time period. Within a set time interval, the current capacity retention rate is approximated to the target capacity retention rate at a first set rate to obtain the corrected capacity retention rate. If the current cell temperature of the power battery is greater than or equal to the cell temperature at the last power-off, the capacity retention rate at the last power-off is used as the current capacity retention rate, and within a set time interval, the current capacity retention rate is approximated to the target capacity retention rate at a second set rate to obtain the corrected capacity retention rate. The second set rate is greater than the first set rate.

[0008] In some embodiments, determining the current capacity retention rate under charge / discharge conditions based on the cumulative ampere-hour integral amount within a set time period, and approximating the current capacity retention rate to a target capacity retention rate at a first set rate within a set time interval to obtain a corrected capacity retention rate, includes: Calculate the cumulative ampere-hours within the specified time period; When the cumulative ampere-hour integral amount is less than or equal to the preset ampere-hour integral amount threshold, it is determined to be a charging condition, and the capacity retention rate at the time of the last power-off is used as the current capacity retention rate without smoothing correction. When the cumulative ampere-hour integral is greater than the preset ampere-hour integral threshold, it is determined to be a discharge condition. The capacity retention rate at the time of the last power-off is used as the current capacity retention rate. The capacity retention rate is gradually approached towards the target capacity retention rate at a first set rate to obtain the corrected capacity retention rate.

[0009] In some embodiments, calculating the true state of charge of the power battery based on the corrected capacity retention rate includes: Calculate the frozen capacity based on the corrected capacity retention rate; Obtain the remaining capacity of the power battery when the vehicle was last powered off, and calculate the true state of charge based on the frozen capacity and the remaining capacity.

[0010] In some embodiments, the true state of charge is calculated using the following formula: True state of charge = (remaining capacity - frozen capacity) / (total capacity of power battery - frozen capacity).

[0011] In some embodiments, the frozen capacity is calculated using the following formula: Frozen capacity = Total capacity of power battery × (1 - Corrected capacity retention rate).

[0012] In some embodiments, the method further includes: When the absolute value of the difference between the corrected capacity retention rate and the target capacity retention rate is less than a preset following threshold and the duration reaches a preset stabilization time, the system enters the following completion state and continuously monitors the changes in the current cell temperature and the target capacity retention rate. If the current cell temperature rises and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the first re-trigger threshold, then the smooth correction is performed again according to the second set rate. If the current cell temperature decreases and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the second re-trigger threshold, then the charging and discharging conditions are re-identified and a smooth correction is performed according to the corresponding strategy. If neither of the above two conditions is met, the corrected capacity retention rate will be directly updated to the target capacity retention rate corresponding to the current temperature at each adjustment cycle, without the need to perform smoothing correction.

[0013] According to some embodiments, the second aspect of the present invention provides an SOE smoothing correction system for electric vehicle power batteries, which adopts the following technical solution: The SOE smoothing correction system for electric vehicle power batteries includes: The target capacity retention rate acquisition module is configured to acquire the current cell temperature and the corresponding target capacity retention rate of the power battery when the vehicle is powered on, based on a preset correspondence between cell temperature and target capacity retention rate. The smoothing correction module is configured to determine the corresponding capacity retention smoothing correction strategy based on the relationship between the current cell temperature and the cell temperature at the last power-off time, so as to obtain the corrected capacity retention rate. The true state of charge (SFC) calculation module is configured to calculate the true state of charge of the power battery based on the corrected capacity retention rate and send it to the vehicle's instrument panel display.

[0014] According to some embodiments, a third aspect of the present invention provides a computer-readable storage medium.

[0015] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the SOE smoothing correction method for an electric vehicle power battery as described in the first embodiment above.

[0016] According to some embodiments, a fifth aspect of the present invention provides an electric vehicle.

[0017] An electric vehicle, comprising: Memory, used to store computer programs; A processor is used to execute the computer program to implement the SOE smoothing correction method for electric vehicle power batteries described in the first scheme above.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses the capacity retention rate at the time of the last power-off as a starting point for smooth correction of the capacity retention rate, rather than directly using the target capacity retention rate corresponding to the current temperature. This effectively avoids the problem of a sudden drop in the instrument's State of Charge (SOC) caused by abrupt changes in the capacity retention rate. By comparing the current cell temperature with the cell temperature at the time of the last power-off, a differentiated correction strategy is adopted: In scenarios where the temperature is decreasing, the cumulative ampere-hours (AH) integral over a set time period is used to accurately identify the charging and discharging conditions. In the discharging condition, the target capacity retention rate is slowly approached at a first set rate to avoid causing user panic due to a rapid drop in SOC after a cold start at extremely low temperatures. In scenarios where the temperature is increasing or remaining constant, the target capacity retention rate is rapidly approached at a second set rate, so that the battery performance recovery is reflected in the instrument display in a timely manner, enhancing the user's confidence in the range. The second set rate is greater than the first set rate, reflecting the differentiated processing principle of rapid response to temperature rise and smooth transition to temperature fall. While improving the accuracy of SOC display, this significantly improves the user experience in scenarios with temperature changes. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a flowchart of a method for smoothing SOE correction of electric vehicle power batteries according to an embodiment of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0025] Terminology Explanation Before describing the technical solution of this application in detail, the core terms involved in this invention will be defined and explained first.

[0026] SOE (State of Energy): Represents the ratio between the actual remaining usable energy of a power battery and its total usable energy. SOE comprehensively considers the impact of factors such as battery efficiency, actual power output capability, temperature effects, battery internal resistance, and aging on the actual usable energy, reflecting the level of energy that the battery can truly release in its current state.

[0027] SOC (State of Charge): Represents the percentage of a battery's current remaining charge relative to its total capacity. SOC primarily focuses on the percentage of remaining battery charge and serves as an "indicator" of charge capacity. In this application, true SOC refers to the percentage of the battery's actual usable charge relative to its total usable capacity, after considering the impact of temperature-induced capacity freezing.

[0028] Capacity retention rate: This indicates the proportion of the actual usable capacity of a power battery to its nominal total capacity under specific temperature conditions. The capacity retention rate varies with temperature; the lower the temperature, the lower the capacity retention rate. For example, the capacity retention rate can reach 100% at a standard temperature of 25°C, while it may drop to 60% at a low temperature of -20°C. The capacity retention rate reflects the degree to which temperature affects the usable capacity of the battery.

[0029] Target capacity retention rate: This refers to the theoretical capacity retention rate value obtained by looking up a pre-calibrated temperature-capacity retention rate mapping table under the currently detected cell temperature conditions. The target capacity retention rate represents the capacity retention rate level that the power battery should have at the current temperature, and is a target value for smooth correction of the capacity retention rate.

[0030] Frozen capacity: This refers to the portion of the battery's capacity that is temporarily unusable due to reduced electrochemical activity at low temperatures. Frozen capacity equals the nominal total capacity of the battery multiplied by (1 - capacity retention rate). For example, a battery with a total capacity of 100 Ah has a frozen capacity of 20 Ah when the capacity retention rate is 80%. Frozen capacity needs to be subtracted from the remaining capacity when calculating the actual State of Charge (SOC).

[0031] Ampere-hour integral quantity: refers to the amount of charge obtained by sampling and accumulating the charging and discharging current of the power battery within a set time period, and the unit is ampere-hour (Ah). The sign and magnitude of the ampere-hour integral quantity can be used to identify the charging and discharging conditions and current intensity.

[0032] As mentioned in the background section, with the popularization of electric vehicles and the development of power battery technology, battery management systems are playing an increasingly important role in ensuring vehicle safety and improving user experience. Among these parameters, SOE (State of Energy) is a key parameter reflecting the actual usable energy of a power battery. Its accuracy directly affects the SOC (State of Charge) value displayed on the instrument panel, thus influencing the user's judgment of the driving range and their confidence in its use. Because the usable capacity of power batteries varies significantly under different temperature environments, especially at low temperatures, some capacity may become temporarily unusable due to reduced electrochemical activity, forming what is known as "frozen capacity." Therefore, accurately calculating and displaying SOE / SOC has become one of the core technical challenges of battery management systems.

[0033] Currently, electric vehicle power battery management systems mainly employ the following two schemes to address the impact of temperature changes on SOE: The first approach is the static lookup table method, which records and stores parameters such as cell temperature, capacity retention rate, and remaining available energy in the system when the vehicle is powered off. When the vehicle is powered on again, the target capacity retention rate corresponding to the currently detected cell temperature is obtained by looking up the table. The frozen capacity is then updated directly with the target capacity retention rate, and the actual SOC is recalculated for the instrument display. The second approach is the SOC tracking approach. Under low-temperature discharge conditions, when the actual SOC drops to 0, the tracking SOC displayed by the system control instrument gradually approaches the actual low-temperature SOC at a fixed rate.

[0034] However, both of the above solutions have significant technical flaws. The static lookup table method, when the temperature changes abruptly (e.g., a vehicle driven from a warm indoor environment into an extremely cold outdoor environment, or a cold start after prolonged idling in extremely low temperatures), directly updates the frozen capacity using the target capacity retention rate, causing the instrument panel's displayed State of Charge (SOC) to drop sharply upon power-up, for example, from 80% to 50%. This creates the illusion for the driver that the driving range has been significantly reduced, severely impacting the user experience. The following SOC solution, in extremely low-temperature cold start scenarios, suffers from an excessively large frozen capacity obtained from the lookup table, resulting in a calculated true SOC of 0 or close to 0. This causes the instrument panel's displayed following SOC to rapidly return to zero at a fixed rate, triggering driver panic about the vehicle's unusability. Furthermore, neither solution differentiates the impact of charging and discharging conditions on the capacity retention rate adjustment strategy. In charging scenarios with decreasing temperatures, the capacity retention rate continues to decrease, resulting in an uneven SOC display on the instrument panel, contradicting the user's expectation that the battery level should increase during charging, further impacting the user experience.

[0035] The root cause of the aforementioned technical problems lies in the fact that existing solutions lack a smoothing mechanism for the process of capacity retention rate changes, and lack differentiated identification and response strategies for charging and discharging conditions.

[0036] Example 1 like Figure 1 As shown, this embodiment provides a method for smoothing SOE correction of electric vehicle power batteries. This embodiment uses the application of this method to a server as an example for illustration. It can be understood that this method can also be applied to terminals, and can also be applied to systems including terminals, servers, and other components, and can be implemented through the interaction between the terminal and the server. The server can be an independent physical server, a server cluster composed of multiple physical servers, or a distributed system. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communication, middleware services, domain name services, CDN security services, and big data and artificial intelligence platforms. The terminal can be a smartphone, tablet computer, laptop computer, desktop computer, smart speaker, smartwatch, etc., but is not limited to these. The terminal and the server can be directly or indirectly connected through wired or wireless communication, which is not limited in this application. In this embodiment, the method includes the following steps: When the vehicle is powered on, the current cell temperature and the corresponding target capacity retention rate of the power battery are obtained according to the preset relationship between cell temperature and target capacity retention rate. Based on the relationship between the current cell temperature and the cell temperature at the last power-off time, a corresponding capacity retention rate smoothing correction strategy is determined to obtain the corrected capacity retention rate. The true state of charge of the power battery is calculated based on the corrected capacity retention rate and sent to the vehicle's instrument panel display.

[0037] The SOE smoothing correction method for electric vehicle power batteries provided in this embodiment has the following core technical idea: Instead of directly updating the frozen capacity using the target capacity retention rate corresponding to the current temperature when the vehicle is powered on, it starts with the capacity retention rate recorded at the last power-off time. Based on the direction of temperature change (rising or falling) and the different charging and discharging conditions (charging or discharging), a differentiated smoothing correction strategy is adopted to gradually approach the target value at a reasonable rate. When the temperature drops, the charging and discharging conditions are identified through ampere-hour integral. Under charging conditions, the capacity retention rate remains unchanged; under discharging conditions, the capacity retention rate decreases at a slower first set rate. When the temperature rises or remains unchanged, the capacity retention rate increases at a faster second set rate. Through this smoothing correction strategy, abrupt changes in the capacity retention rate are avoided, thus ensuring smooth changes in both the actual SOC calculated based on the capacity retention rate and the SOC displayed on the instrument panel. This solves the SOC abrupt change problem caused by the static lookup table method, the rapid zeroing problem caused by the SOC following the SOC scheme, and the display unsmoothness problem caused by the lack of differentiated processing of charging and discharging conditions, significantly improving the user experience in temperature-changing scenarios.

[0038] Specifically, the technical solution of this application includes the following key technical points: (1) Dual-dimensional judgment mechanism: The system first judges the direction of temperature change (the relationship between the current temperature and the temperature at the last power-off time) to determine whether it is a temperature rise scenario or a temperature fall scenario. In the temperature fall scenario, the charging and discharging conditions are further identified by calculating the cumulative ampere-hour integral amount within a set time period, thus realizing dual-dimensional judgment.

[0039] (2) Differentiated smoothing correction strategy: When the temperature drops, the capacity retention rate is kept constant during charging to avoid abnormal fluctuations in the SOC display; during discharging, the capacity retention rate is reduced at the first set rate to truly reflect the gradual reduction of available energy. When the temperature rises or remains constant, the capacity retention rate is increased at the second set rate to quickly restore the available capacity display.

[0040] (3) Ah-hour integral quantity condition identification: By calculating the cumulative ampere-hour integral quantity within a set time period (e.g., 1 minute) and comparing it with a preset ampere-hour integral quantity threshold, the charging and discharging conditions are accurately identified. This method can effectively avoid misjudgment caused by instantaneous current fluctuations and improve the accuracy and stability of condition identification.

[0041] (4) Re-triggering mechanism: After the capacity retention rate is completed, the system continuously monitors the changes in temperature and capacity retention rate. If the temperature changes significantly again, causing the change in the target capacity retention rate to exceed the preset threshold, the smoothing correction process is re-triggered to ensure that the system can adapt to dynamic temperature changes.

[0042] By employing the aforementioned smoothing correction strategy, abrupt changes in capacity retention rate are avoided, thereby ensuring smooth changes in both the actual SOC calculated based on capacity retention rate and the SOC displayed on the instrument. This solves the problems of SOC abrupt changes caused by the static lookup table method, the rapid zeroing problem caused by the SOC following scheme, and the unsmooth display problem caused by the lack of differentiated processing of charging and discharging conditions, significantly improving the user experience in scenarios with temperature changes.

[0043] An example environment in which embodiments of this application can be implemented is provided, the example environment including an electric vehicle, a power battery pack, a battery management system, a vehicle instrument panel, a temperature sensor, a current sensor, and a CAN bus.

[0044] Electric vehicles are the application carriers of the technical solutions in this application, and can be pure electric passenger vehicles, hybrid electric vehicles, or other types of electric vehicles. The power battery pack provides driving energy for the electric vehicle and is typically composed of multiple individual battery cells connected in series and parallel. In this embodiment, the nominal total capacity of the power battery pack is 100Ah, and the operating voltage range is 250V to 420V. The power battery pack uses ternary lithium-ion batteries, and its capacity retention rate varies with temperature as follows: 100% capacity retention rate at 25℃, approximately 90% at 0℃, approximately 85% at -10℃, approximately 60% at -20℃, and approximately 40% at -30℃.

[0045] The Battery Management System (BMS) is the main implementing entity of the technical solution in this application. It is responsible for monitoring the operating status of the power battery pack, executing the capacity retention rate smoothing correction algorithm, calculating the true State of Charge (SOC), and sending the SOC value to the vehicle's instrument panel for display via the CAN bus. The BMS includes a microprocessor, non-volatile memory, a current sensor interface, a temperature sensor interface, and a CAN communication module. The microprocessor uses a 32-bit ARM Cortex-M4 core with a clock speed of 168MHz and a floating-point arithmetic unit, enabling efficient execution of capacity retention rate and SOC calculation algorithms. The non-volatile memory uses EEPROM or Flash memory to store key parameters (including cell temperature, capacity retention rate, and remaining capacity) when the vehicle is powered off, and to retrieve these parameters when the vehicle is powered on again. The non-volatile memory also stores a temperature-capacity retention rate mapping table, which was obtained through capacity calibration tests on the power battery pack under different temperature conditions, covering a temperature range of -40℃ to 60℃, with temperature intervals of 5℃.

[0046] Temperature sensors are used to monitor the cell temperature of the power battery pack in real time. These sensors employ NTC (negative temperature coefficient) thermistors and are installed at key locations within the battery module. Current sensors are used to monitor the charging and discharging current of the power battery pack in real time. These sensors employ Hall effect current sensors with a measurement range of -400A to +400A, a measurement accuracy of ±0.5%, and a current sampling frequency of 10Hz (sampled every 100ms). Discharging current is defined as positive, and charging current as negative. The vehicle's instrument panel receives SOC data from the battery management system via the CAN bus and displays it as a percentage on the dashboard. The CAN bus communication rate is 500kbps, and the battery management system sends messages containing the SOC value to the CAN bus every 100ms.

[0047] The typical application scenario of this technical solution in the above-mentioned example environment is as follows: An electric vehicle is used in a cold winter region and parked overnight in a parking lot with an outdoor ambient temperature of -20℃. When the vehicle is powered off, the cell temperature is -15℃, the capacity retention rate is 75%, and the remaining capacity is 60Ah. The next morning, the driver starts the vehicle. At this time, the ambient temperature is still -20℃, and the cell temperature has dropped to -20℃. According to the temperature-capacity retention rate mapping table, the target capacity retention rate is 60%. If the traditional static lookup table method is used, the system will immediately calculate the frozen capacity as 40Ah based on the 60% capacity retention rate. The actual SOC is (60-40) / (100-40) = 33.3%. The instrument panel shows that the SOC suddenly drops from approximately 75% before power-off to 33.3%, giving the driver the illusion of a significant reduction in range. By adopting the smooth correction method of this application, the system starts with a capacity retention rate of 75%. During the driver's operation of the vehicle (discharge condition), the capacity retention rate gradually decreases at a first set rate of 0.5% per minute, and drops to 60% after 30 minutes. During this process, the SOC displayed on the instrument panel decreases smoothly, avoiding sudden changes and improving the user experience.

[0048] It should be understood that the above example environments are only used to illustrate the application scenarios of the technical solutions of this application and do not constitute a limitation on the scope of protection of this application. The technical solutions of this application can be applied to various types of electric vehicles and their battery management systems, as well as other scenarios that require battery SOE / SOC management, such as energy storage systems, power tools, etc.

[0049] Specifically, the detailed process of the method described in this embodiment includes: Step S101: When the vehicle is powered on, obtain the current cell temperature of the power battery and the corresponding target capacity retention rate. When the driver starts the vehicle using the key or push-button start, the vehicle's IGN (ignition) signal changes from low to high, triggering the battery management system to power on and begin operation. The battery management system's microprocessor then transitions from a reset state to normal operation and begins executing the capacity retention rate smoothing correction algorithm stored in the program memory.

[0050] First, the microprocessor acquires the current cell temperature Tr through a temperature sensor interface. Specifically, the microprocessor controls the ADC to sample and convert the analog voltage signals connected to each NTC thermistor. The NTC thermistor and a pull-up resistor of known value form a voltage divider circuit, and the ADC samples the voltage value at the divider point. Based on the sampled voltage value, the microprocessor looks up a pre-stored voltage-to-temperature conversion table and calculates the corresponding temperature value through linear interpolation. The microprocessor acquires the temperature values ​​from all temperature sensors (e.g., eight temperature sensors) arranged inside the battery pack and calculates the average value as the current cell temperature Tr. To suppress random noise in the temperature measurement, the microprocessor performs a first-order low-pass digital filter on the acquired temperature value.

[0051] Secondly, the microprocessor reads key parameters stored from the non-volatile memory when the vehicle was last powered off, including the cell temperature (Tf), capacity retention rate (SOEf), and remaining capacity at the time of the last power-off. Before powering off, the non-volatile memory writes these key parameters to a designated address and calculates and stores a CRC (Cyclic Redundancy Check) checksum. When the vehicle is powered on again, the microprocessor reads these parameters and the CRC checksum from the non-volatile memory, performs a CRC check on the read data, and if the check passes, the data is considered valid; otherwise, the default parameters (Tf = 25℃, SOEf = 100%) are used.

[0052] Next, the microprocessor queries the temperature-capacity retention rate mapping table stored in non-volatile memory based on the current cell temperature Tr to obtain the target capacity retention rate SOEr corresponding to the current temperature. This mapping table is obtained by performing capacity calibration tests on the power battery pack at 5°C intervals within the range of -40°C to 60°C. When the current cell temperature Tr is not a calibrated temperature point in the table, the microprocessor uses a linear interpolation method to calculate the target capacity retention rate SOEr. For example, if the current cell temperature Tr is -18°C, and the table shows a capacity retention rate of 75% for -15°C and 60% for -20°C, then the target capacity retention rate SOEr is calculated using linear interpolation.

[0053] The technical problem addressed by step S101 is to accurately acquire the current temperature and historical parameters when the vehicle is powered on, providing a data foundation for determining the direction of temperature change and performing smoothing correction. The technical effect of step S101 is that, through techniques such as temperature sampling, digital filtering, non-volatile memory reading, CRC verification, and lookup table interpolation, the acquired temperature and capacity retention data are ensured to be accurate and reliable, laying the foundation for the correct execution of the subsequent smoothing correction algorithm.

[0054] Step S102: Temperature comparison and judgment - Determine the relationship between the current cell temperature and the cell temperature at the last power-off time, and determine the direction of temperature change; The microprocessor compares the current cell temperature Tr obtained in step S101 with the cell temperature Tf at the last power-off time to determine the direction of temperature change. The specific determination logic is as follows: If Tr is less than Tf, it is determined to be a temperature decrease scenario. The temperature change direction flag is set to "temperature decrease", and the temperature decrease branch processing flow of step S103 is executed subsequently.

[0055] If Tr is greater than or equal to Tf, it is determined to be a scenario of temperature rising or temperature remaining unchanged. The temperature change direction flag is set to "temperature rising", and the temperature rise branch processing flow of step S104 is executed subsequently.

[0056] In this embodiment, when Tr equals Tf, meaning the temperature remains unchanged, it is classified into the temperature rise branch. This is because, theoretically, the capacity retention rate should also remain unchanged when the temperature is constant. However, considering the errors in temperature measurement and the slight fluctuations in the battery's own temperature, to avoid frequent switching of processing branches, the scenario with constant temperature is classified into the temperature rise branch, and a second set rate is used to make the capacity retention rate quickly approach the target value, thereby quickly completing the following process.

[0057] The second set rate refers to the adjustment rate at which the current capacity retention rate approaches the target capacity retention rate when the temperature rises or remains constant. The second set rate is a rapid adjustment rate, with the capacity retention rate increasing by 1% to 5% per adjustment cycle, preferably 2% per minute. Using a faster adjustment rate allows for quick recovery of usable capacity when the temperature rises, increasing user confidence in battery life. The second set rate is greater than the first set rate, reflecting a differentiated processing strategy for rising and falling temperatures. In this application, the second set rate is typically 2 to 10 times the first set rate, preferably 4 times. Rising temperature means increased battery capacity, and this increase should be reflected in the instrument display as quickly as possible; therefore, a faster adjustment rate is used.

[0058] The technical problem solved by step S102 is to accurately identify the direction of temperature change, providing a basis for selecting an appropriate capacity retention adjustment strategy. The technical effect of step S102 is that, through simple temperature magnitude comparison, the direction of temperature change is accurately identified, providing the correct branch selection for the subsequent execution of the differentiated smoothing correction strategy.

[0059] Step S103: Temperature drop branch - Determine the charging and discharging conditions based on the cumulative ampere-hour integral amount within the set time period, and execute a differentiated smoothing correction strategy; When step S102 determines that the scenario is a temperature drop (Tr is less than Tf), the microprocessor executes the temperature drop branch processing flow in step S103. The core of this process is to identify the charging and discharging conditions by calculating the cumulative ampere-hour integral amount within a set time period, and to adopt different capacity retention rate adjustment strategies according to the type of operating condition.

[0060] Step S103-1: Calculate the cumulative ampere-hours within the set time period. The microprocessor continuously acquires the charging and discharging current values ​​of the power battery pack through the current sensor interface at a sampling period of 100ms. ,in The sampling sequence number is used, with the discharge current defined as a positive value and the charging current as a negative value. The microprocessor accumulates and sums the collected current values ​​within a set time period (in this embodiment, the set time period is 1 minute, or 60 seconds) to calculate the cumulative ampere-hour integral. The calculation formula is:

[0061] in, For the first The current value of each sample is in amperes (A). In this embodiment, the sampling time interval is... seconds (100ms); This represents the summation of all sampling points within a set time period. In a 1-minute time period, a total of 600 current samples were taken (60 seconds ÷ 0.1 seconds = 600 samples). The cumulative ampere-hour integral is... The sign and magnitude of the value reflect the charging and discharging conditions and current intensity within a set time period. A positive value indicates that discharge is dominant. A negative value indicates that charging is the dominant process.

[0062] Step S103-2: Compare the cumulative ampere-hour integral with the preset ampere-hour integral threshold to identify the charging and discharging conditions. The microprocessor will calculate the cumulative ampere-hour integral value obtained in step S103-1. Compared with the preset ampere-hour integral threshold The comparison identifies whether the current operation is charging or discharging. A preset ampere-hour integral threshold is set. The calculation formula is:

[0063] in, The preset current threshold value ranges from 1A to 5A, and is preferably 2A in this embodiment; The time period is set, which is 60 seconds (1 minute) in this embodiment. Therefore, the ampere-hour integral threshold is preset.

[0064] like Less than or equal to If the current is low, it is considered a charging condition. Here, "charging condition" is used broadly, including not only scenarios where an external charging station charges the battery, but also scenarios where the vehicle is stationary (when the current is close to zero). Approaching 0), energy recovery during vehicle coasting or braking (at which point the current is negative), (For scenarios such as negative values).

[0065] like Greater than If the signal is positive, it is considered a discharge condition. This indicates that the power battery pack continuously discharges at a large current within a set time period, such as when the vehicle is driving, accelerating, or climbing a hill.

[0066] Step S103-3: Implement differentiated capacity retention rate adjustment strategies based on operating condition type. Scenario 1: Charging condition ( — Maintaining a constant capacity retention rate When the system is identified as charging, the microprocessor does not adjust the capacity retention rate, but keeps the capacity retention rate SOEf from the last power-off as the current capacity retention rate. That is, the current capacity retention rate = SOEf, without smoothing correction, the frozen capacity remains unchanged, and the calculation of the actual SOC is based on the unchanged frozen capacity.

[0067] The technical reason for adopting this strategy is that, during charging, the power battery pack is not in a continuous discharge state, and the available capacity of the battery does not decrease due to discharge; therefore, the capacity retention rate should not decrease. If the capacity retention rate continues to decrease during charging, it will lead to an increase in the calculated frozen capacity, a decrease in the actual SOC, and a drop in the SOC displayed on the instrument panel. This contradicts the user's expectation that the battery capacity should increase during charging, resulting in an uneven display and affecting the user experience.

[0068] For example: After starting the vehicle in an environment of -20℃, it does not drive immediately but remains stationary inside the vehicle (at this time, the current is close to 0, and the cumulative ampere-hour integral is...). If the value is close to 0 but less than the threshold of 0.0333Ah, the system determines that it is in charging condition. The capacity retention rate remains unchanged at 75% of the value at the time of the last power-off, the frozen capacity remains at 25Ah, the actual SOC remains stable, and the SOC displayed on the instrument will not decrease.

[0069] Scenario 2: Discharge condition ( — Gradually reduce the capacity retention rate at the first set rate; When a discharge condition is detected, the microprocessor initiates a capacity retention rate smoothing correction algorithm. Starting from the capacity retention rate SOEf at the time of the last power-off, it gradually approaches the target capacity retention rate SOEr at a first set rate. The first set rate is a slow adjustment rate, and its value ranges from 0.1% to 1% of the capacity retention rate per adjustment cycle. In this embodiment, the adjustment cycle is set to 1 minute, and the first set rate is preferably 0.5% per minute.

[0070] At the end of each adjustment cycle (1 minute), the microprocessor updates the capacity retention rate: Current capacity retention rate (new) = Current capacity retention rate (old) - 0.5%.

[0071] The first set rate refers to the adjustment rate at which the current capacity retention rate approaches the target capacity retention rate when the temperature drops and the battery is in discharge condition. The first set rate is a slow adjustment rate, with the capacity retention rate decreasing by 0.1% to 1% per adjustment cycle, preferably 0.5% per minute. Using a slower adjustment rate avoids excessively rapid drops in the State of Charge (SOC) displayed on the instrument during low-temperature discharge, improving the user experience. The principle for setting the first set rate is to accurately reflect the gradual reduction of available battery energy while avoiding excessively rapid SOC drops that could cause user anxiety. In this application, the first set rate can be adjusted according to the actual application scenario; for example, the adjustment rate can be appropriately reduced in extremely cold regions and appropriately increased in temperate regions.

[0072] For example: Assume that when the power was last applied, Tf=0℃, and the capacity retention rate SOEf=85%. Currently, Tr=-20℃, and the target capacity retention rate SOEr=60%. Initially, the current capacity retention rate is 85%. After the first adjustment cycle (1 minute), it is updated to 85%-0.5%=84.5%; after the second adjustment cycle, it is updated to 84.5%-0.5%=84%; and so on, decreasing by 0.5% every minute, reaching 60% after 50 minutes, thus completing the catch-up process. During this 50-minute smooth correction process, the capacity retention rate gradually decreases from 85% to 60%, the frozen capacity gradually increases from 15Ah to 40Ah, the actual SOC gradually decreases, and the SOC displayed on the instrument decreases smoothly, avoiding abrupt changes.

[0073] It should be noted that during the capacity retention rate smoothing correction process, the microprocessor recalculates the cumulative ampere-hour integral at the beginning of each adjustment cycle. The microprocessor re-identifies the charging and discharging conditions. If the conditions change during the smoothing correction process (e.g., switching from discharging to charging), the microprocessor adjusts its processing strategy accordingly, stops reducing the capacity retention rate, and keeps the current value unchanged.

[0074] The technical problem addressed by step S103 is: in scenarios with decreasing temperatures, by identifying charging and discharging conditions and adopting differentiated adjustment strategies, unreasonable reductions in capacity retention rate are avoided during charging, while a slower rate of capacity retention rate reduction occurs during discharging, ensuring a smooth decrease in the instrument's State of Charge (SOC). The technical effect of step S103 is: through ampere-hour integral calculation, operating condition identification, differentiated adjustment strategies, and slow smooth correction, the problem of sudden changes or rapid zeroing of the instrument's SOC in traditional solutions during temperature-decreasing scenarios is solved, significantly improving the user experience.

[0075] Step S104: Temperature Rise / Unchanged Branch – Starting from the capacity retention rate at the time of the last power-off, rapidly approach the target capacity retention rate at the second set rate. When step S102 determines that the temperature is rising or remaining constant (Tr≥Tf), the microprocessor executes the temperature rise branch processing flow in step S104. The core of this process is: taking the capacity retention rate SOEf at the time of the last power-off as the starting point, it rapidly approaches the target capacity retention rate SOEr at a second set rate, without needing to identify the charging and discharging conditions, and using the same rapid approximation strategy for both charging and discharging.

[0076] Step S104-1: Determine the initial value of capacity retention. The microprocessor uses the capacity retention rate SOEf at the last power-down as the initial value of the current capacity retention rate, that is, the current capacity retention rate (initial) = SOEf.

[0077] Step S104-2: Gradually increase the capacity retention rate according to the second set rate. The second set rate is the rapid adjustment rate, and its value range is: the capacity retention rate increases by 1% to 5% in each adjustment cycle. In this embodiment, the adjustment cycle is set to 1 minute, and the second set rate is preferably increased by 2% per minute.

[0078] At the end of each adjustment cycle (1 minute), the microprocessor updates the capacity retention rate: Current capacity retention rate (new) = Current capacity retention rate (old) + 2%.

[0079] For example: Assume that when the battery was last powered on, Tf = -10℃, and the capacity retention rate SOEf = 75%. Currently, Tr = 10℃, and the target capacity retention rate SOEr = 95%. Initially, the current capacity retention rate is 75%. After the first adjustment cycle (1 minute), it updates to 75% + 2% = 77%; after the second adjustment cycle, it updates to 77% + 2% = 79%; and so on, increasing by 2% every minute, reaching 95% after 10 minutes, thus completing the catch-up process. During this 10-minute smooth correction process, the capacity retention rate gradually increases from 75% to 95%, the frozen capacity gradually decreases from 25Ah to 5Ah, the actual SOC gradually increases, and the SOC displayed on the instrument rises smoothly, quickly reflecting the actual increase in usable battery capacity after the temperature rises.

[0080] Analysis of the technical reason why the second set rate (2% increase per minute) is greater than the first set rate (0.5% decrease per minute): Rising temperature means increased battery capacity, and this increase should be reflected in the State of Charge (SOC) displayed on the instrument panel as quickly as possible, allowing the driver to understand the improved range and boosting user confidence. Therefore, a faster adjustment rate is used. Conversely, if the adjustment rate is too fast when the temperature drops, the SOC on the instrument panel will decrease rapidly, causing anxiety for the user due to a significant reduction in range. Therefore, a slower adjustment rate is used to allow the SOC to decrease smoothly, improving the user experience.

[0081] The technical problem solved by step S104 is: in scenarios where the temperature rises, to quickly increase the capacity retention rate to the target value, so that the increased available capacity is reflected in the SOC displayed on the instrument panel as soon as possible, thereby improving the user's perception of the restored battery life. The technical effect of step S104 is: through a faster second setting rate, to complete the follow-up of the capacity retention rate in a shorter time, quickly restore the SOC display on the instrument panel, enhance user confidence, and improve the user experience.

[0082] Step S105: Calculate the true state of charge of the power battery based on the corrected capacity retention rate and send it to the vehicle instrument display. Whether executing the temperature decrease branch of step S103 or the temperature increase branch of step S104, the microprocessor obtains the corrected capacity retention rate at the end of each adjustment cycle. Based on the corrected capacity retention rate, the microprocessor calculates the true state of charge (true SOC) of the power battery and sends the true SOC to the vehicle instrument panel 130 for display via the CAN bus 160.

[0083] Step S105-1: Calculate the frozen capacity based on the corrected capacity retention rate. The formula for calculating the frozen capacity is:

[0084] in, To freeze the volume, The total capacity of the power battery This is the corrected capacity retention rate.

[0085] For example, if the total capacity of the power battery is 100Ah and the corrected capacity retention rate is 70%, then the frozen capacity = 100Ah × (1-70%) = 30Ah.

[0086] Step S105-2: Obtain the remaining capacity of the power battery when the vehicle was last powered off. ; When the vehicle is powered off, the microprocessor stores the current remaining capacity in non-volatile memory; when the vehicle is powered on again, the microprocessor reads the remaining capacity from the non-volatile memory at the time of the last power-off as the initial value of the current remaining capacity, and continuously updates it based on the current integral during vehicle operation.

[0087] Step S105-3: Calculate the true state of charge based on the frozen capacity and remaining capacity; The formula for calculating the actual SOC is:

[0088] The physical meaning of this formula is: the numerator (remaining capacity - frozen capacity) represents the actual usable power after deducting the frozen capacity, and the denominator (total capacity - frozen capacity) represents the actual total usable capacity after deducting the frozen capacity. The ratio of the two is the true SOC.

[0089] For example: If the total capacity of the power battery is 100Ah, the corrected capacity retention rate is 80%, the frozen capacity is 20Ah, and the remaining capacity is 76Ah, then the true SOC = (76Ah - 20Ah) / (100Ah - 20Ah) = 56Ah ÷ 80Ah = 70%.

[0090] Step S105-4: Send the actual SOC to the vehicle instrument panel display via the CAN bus. The microprocessor encapsulates the calculated true SOC value into a CAN message and sends it to the CAN bus via the CAN communication module. The battery management system sends a message containing the true SOC to the CAN bus every 100ms. After receiving the CAN message, the vehicle's instrument panel parses and displays the true SOC value.

[0091] The technical problem solved by step S105 is to accurately calculate the true State of Charge (SOC) based on the corrected capacity retention rate and send it to the instrument display, enabling the driver to know the actual available power of the battery. The technical effect of step S105 is that by freezing capacity calculation, true SOC calculation, and CAN communication, accurate calculation and real-time display of the true SOC are achieved, providing the driver with reliable power information and improving the user experience.

[0092] VI. Re-triggering logic after follow-up is completed During the smooth correction of capacity retention rate, the current capacity retention rate gradually approaches the target capacity retention rate. When the absolute value of the difference between the corrected capacity retention rate and the target capacity retention rate is less than the preset following threshold (ranging from 0.1% to 1%, preferably 0.5%) and remains stable for a preset time (ranging from 1 minute to 10 minutes, preferably 3 minutes), the microprocessor determines that the capacity retention rate has been followed and enters the following completion state.

[0093] Once the follow-up process is complete, the microprocessor continuously monitors changes in the current cell temperature and target capacity retention rate, and determines whether to re-trigger smoothing correction based on these changes. There are three possible processing scenarios: Case 1: If the current cell temperature rises and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the first re-trigger threshold, then the smoothing correction is re-executed according to the second set rate. The first re-trigger threshold ranges from 1% to 5%, preferably 2%. For example: when the follow-up is complete, the current cell temperature is 0℃, and the corrected capacity retention rate is 80%. Subsequently, due to the battery's own heating, the cell temperature rises to 10℃, and a new target capacity retention rate of 90% is obtained from the table. The temperature rises (10℃ is greater than 0℃), and the change in the target capacity retention rate is 90% - 80% = 10%, which is greater than the first re-trigger threshold of 2%, thus satisfying the re-trigger condition. The microprocessor re-triggers the smooth correction, starting from 80%, and approaches the new target capacity retention rate of 90% at a second set rate (accumulating 2% per minute).

[0094] Case 2: If the current cell temperature decreases and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the second re-trigger threshold, then the charging and discharging conditions are re-identified and a smooth correction is performed according to the corresponding strategy. The second re-trigger threshold ranges from 0.5% to 2%, preferably 1%. For example: when the tracking is complete, the current cell temperature is 10℃, and the corrected capacity retention rate is 90%. Subsequently, the vehicle enters a cold environment, and the cell temperature drops to -5℃. Looking up the table, the new target capacity retention rate is 75%. The temperature decreases (-5℃ is less than 10℃), and the change in the target capacity retention rate is |75%-90%|=15%, which is greater than the second re-trigger threshold of 1%, thus meeting the re-trigger condition. The microprocessor re-triggers the smooth correction, recalculates the cumulative ampere-hour integral, and identifies the charging / discharging condition. If it is a charging condition, the capacity retention rate remains unchanged at 90%; if it is a discharging condition, it starts from 90% and approaches the new target capacity retention rate of 75% at a first set rate (decreasing by 0.5% per minute).

[0095] Case 3: If neither of the above two cases is satisfied, then at each adjustment interval, the corrected capacity retention rate is directly updated to the target capacity retention rate corresponding to the current temperature, without the need for smoothing correction. This scenario corresponds to a stable temperature and capacity retention rate, where minor changes can be directly updated without causing abrupt changes in the display. For example, when the follow-up is complete, the current cell temperature is 10°C, and the corrected capacity retention rate is 90%. Subsequently, the cell temperature rises slightly to 11°C, and the new target capacity retention rate is 91% (looked up from the table). The temperature increases (11°C is greater than 10°C), but the change in the target capacity retention rate is 91% - 90% = 1%, which is less than the first re-trigger threshold of 2%, thus not meeting the re-trigger condition. The microprocessor directly updates the corrected capacity retention rate to 91% every adjustment cycle (1 minute), without needing to perform a smoothing correction.

[0096] Example 2 This embodiment provides an SOE smoothing correction system for electric vehicle power batteries, including: The target capacity retention rate acquisition module is configured to acquire the current cell temperature and the corresponding target capacity retention rate of the power battery when the vehicle is powered on, based on a preset correspondence between cell temperature and target capacity retention rate. Specifically, this module includes a temperature acquisition unit, a historical parameter reading unit, and a target capacity retention rate query unit. The temperature acquisition unit acquires temperature values ​​from multiple temperature sensors inside the battery pack via a temperature sensor interface, calculates the average value, and performs digital filtering to obtain the current cell temperature Tr. The historical parameter reading unit reads key parameters (Tf, SOEf, remaining capacity) stored in non-volatile memory from the last time the vehicle was powered off, and performs CRC verification on the read data. The target capacity retention rate query unit queries the temperature-capacity retention rate mapping table based on the current cell temperature Tr and calculates the target capacity retention rate SOEr through linear interpolation.

[0097] The smoothing correction module is configured to determine the corresponding capacity retention smoothing correction strategy based on the relationship between the current cell temperature and the cell temperature at the last power-off time, so as to obtain the corrected capacity retention rate. Specifically, the smoothing correction module 320 includes a temperature comparison unit 321, a temperature decrease processing unit 322, and a temperature increase processing unit 323. The temperature comparison unit 321 compares the current cell temperature Tr with the cell temperature Tf at the last power-off. If Tr is less than Tf, control is transferred to the temperature decrease processing unit 322; if Tr is greater than or equal to Tf, control is transferred to the temperature increase processing unit 323. The temperature decrease processing unit 322 includes an ampere-hour integral calculation subunit, an operating condition identification subunit, and a differential adjustment subunit. Under charging conditions, it keeps SOEf constant; under discharging conditions, it gradually approaches SOEr at a first set rate (decreasing by 0.5% per minute). The temperature increase processing unit 323 starts at SOEf and gradually approaches SOEr at a second set rate (increasing by 2% per minute).

[0098] The true state of charge (SFC) calculation module is configured to calculate the true state of charge of the power battery based on the corrected capacity retention rate and send it to the vehicle's instrument panel display.

[0099] Specifically, the module includes a frozen capacity calculation unit (frozen capacity = total capacity × (1 - corrected capacity retention rate)), a real SOC calculation unit (real SOC = (remaining capacity - frozen capacity) / (total capacity - frozen capacity)) and a communication transmission unit (encapsulating the real SOC into a CAN message and sending it to the CAN bus).

[0100] The data connection relationships between the modules are as follows: the target capacity retention rate acquisition module 310 transmits Tr, Tf, SOEf, SOEr and remaining capacity to the smoothing correction module 320; the smoothing correction module 320 transmits the corrected capacity retention rate to the real charge calculation module 330; the real charge calculation module 330 sends the real SOC to the vehicle instrument panel via the CAN bus.

[0101] The examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1 above. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0102] The descriptions of each embodiment in the above embodiments have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0103] The proposed system can be implemented in other ways. For example, the system embodiments described above are merely illustrative, and the division of modules described above is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed.

[0104] Example 3 This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the electric vehicle power battery SOE smoothing correction method described in Embodiment 1 above.

[0105] Example 4 This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the electric vehicle power battery SOE smoothing correction method described in Embodiment 1 above.

[0106] Example 5 This embodiment provides an electric vehicle, including: Memory, used to store computer programs; A processor is used to execute the computer program to implement the SOE smoothing correction method for electric vehicle power batteries described in Embodiment 1 above.

[0107] The steps involved in Examples 2 to 5 above correspond to those in Example 1. For specific implementation details, please refer to the relevant description section of Example 1.

[0108] Those skilled in the art will understand that embodiments of the present invention can provide methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0109] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0110] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0111] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0112] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0113] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for smoothing SOE correction of electric vehicle power batteries, characterized in that, Battery management systems for electric vehicles include: When the vehicle is powered on, the current cell temperature and the corresponding target capacity retention rate of the power battery are obtained according to the preset relationship between cell temperature and target capacity retention rate. Based on the relationship between the current cell temperature and the cell temperature at the last power-off time, a corresponding capacity retention rate smoothing correction strategy is determined to obtain the corrected capacity retention rate. The true state of charge of the power battery is calculated based on the corrected capacity retention rate and sent to the vehicle's instrument panel display.

2. The method for smoothing SOE correction of electric vehicle power batteries as described in claim 1, characterized in that, Based on the relationship between the current cell temperature and the cell temperature at the time of the last power-off, a corresponding capacity retention smoothing correction strategy is determined to obtain the corrected capacity retention rate, including: If the current cell temperature of the power battery is lower than the cell temperature when it was last powered off, the current capacity retention rate under the charging and discharging conditions is determined based on the cumulative ampere-hour integral amount within a set time period. Within a set time interval, the current capacity retention rate is approximated to the target capacity retention rate at a first set rate to obtain the corrected capacity retention rate. If the current cell temperature of the power battery is greater than or equal to the cell temperature at the last power-off, the capacity retention rate at the last power-off is used as the current capacity retention rate, and within a set time interval, the current capacity retention rate is approximated to the target capacity retention rate at a second set rate to obtain the corrected capacity retention rate. The second set rate is greater than the first set rate.

3. The method for smoothing SOE correction of electric vehicle power batteries as described in claim 2, characterized in that, The step of determining the current capacity retention rate under charge / discharge conditions based on the cumulative ampere-hour integral amount within a set time period, and approximating the current capacity retention rate to the target capacity retention rate at a first set rate within a set time interval to obtain the corrected capacity retention rate includes: Calculate the cumulative ampere-hours within the specified time period; When the cumulative ampere-hour integral amount is less than or equal to the preset ampere-hour integral amount threshold, it is determined to be a charging condition, and the capacity retention rate at the time of the last power-off is used as the current capacity retention rate without smoothing correction. When the cumulative ampere-hour integral is greater than the preset ampere-hour integral threshold, it is determined to be a discharge condition. The capacity retention rate at the time of the last power-off is used as the current capacity retention rate. The capacity retention rate is gradually approached towards the target capacity retention rate at a first set rate to obtain the corrected capacity retention rate.

4. The method for smoothing SOE correction of electric vehicle power batteries as described in claim 1, characterized in that, The calculation of the true state of charge of the power battery based on the corrected capacity retention rate includes: Calculate the frozen capacity based on the corrected capacity retention rate; Obtain the remaining capacity of the power battery when the vehicle was last powered off, and calculate the true state of charge based on the frozen capacity and the remaining capacity.

5. The SOE smoothing correction method for electric vehicle power batteries as described in claim 4, characterized in that, The true state of charge is calculated using the following formula: True state of charge = (remaining capacity - frozen capacity) / (total capacity of power battery - frozen capacity).

6. The method for smoothing SOE of electric vehicle power batteries as described in claim 4, characterized in that, The frozen capacity is calculated using the following formula: Frozen capacity = Total capacity of power battery × (1 - Corrected capacity retention rate).

7. The method for smoothing SOE correction of electric vehicle power batteries as described in claim 1, characterized in that, The method further includes: When the absolute value of the difference between the corrected capacity retention rate and the target capacity retention rate is less than a preset following threshold and the duration reaches a preset stabilization time, the system enters the following completion state and continuously monitors the changes in the current cell temperature and the target capacity retention rate. If the current cell temperature rises and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the first re-trigger threshold, then the smooth correction is performed again according to the second set rate. If the current cell temperature decreases and the change in the target capacity retention rate relative to the corrected capacity retention rate is greater than the second re-trigger threshold, then the charging and discharging conditions are re-identified and a smooth correction is performed according to the corresponding strategy. If neither of the above two conditions is met, the corrected capacity retention rate will be directly updated to the target capacity retention rate corresponding to the current temperature at each adjustment cycle, without the need to perform smoothing correction.

8. An SOE smoothing correction system for electric vehicle power batteries, characterized in that, include: The target capacity retention rate acquisition module is configured to acquire the current cell temperature and the corresponding target capacity retention rate of the power battery when the vehicle is powered on, based on a preset correspondence between cell temperature and target capacity retention rate. The smoothing correction module is configured to determine the corresponding capacity retention smoothing correction strategy based on the relationship between the current cell temperature and the cell temperature at the last power-off time, so as to obtain the corrected capacity retention rate. The true state of charge (SFC) calculation module is configured to calculate the true state of charge of the power battery based on the corrected capacity retention rate and send it to the vehicle's instrument panel display.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the electric vehicle power battery SOE smoothing correction method as described in any one of claims 1-7.

10. An electric vehicle, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps in the electric vehicle power battery SOE smoothing correction method as described in any one of claims 1-7.

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