Battery undervoltage diagnosis and alarm method and system and vehicle

Abstract

The invention provides a battery undervoltage diagnosis and alarm method and system and a vehicle, and the method comprises the steps: firstly, determining the corresponding relation between the battery temperature and a voltage alarm threshold value based on a plurality of battery temperature data and a plurality of corresponding voltage alarm threshold value data; secondly, detecting the current temperature and the current voltage of the single battery, then determining a target voltage alarm threshold value corresponding to the current temperature according to the corresponding relation, and then determining whether the single battery has undervoltage or not according to a comparison result of the current voltage and the target voltage alarm threshold value; the method comprises the following steps: determining the undervoltage type as transient undervoltage or steady-state undervoltage and determining the undervoltage grade when determining that the battery monomer is undervoltage, and finally triggering a corresponding undervoltage alarm according to the undervoltage grade when determining that the undervoltage type is steady-state undervoltage; therefore, the under-voltage condition of the battery can be accurately diagnosed, and the rationality and effectiveness of under-voltage alarm can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a method, system, and vehicle for diagnosing and alarming undervoltage batteries. Background Technology

[0002] Most new energy vehicles use lithium iron phosphate batteries for power. The nominal voltage of lithium iron phosphate batteries is 3.2V, and their normal operating voltage range is generally between 2.5V and 3.65V. When the battery operates within a reasonable voltage range, the battery output is better and the battery health is higher. Undervoltage operation may cause damage to the battery structure and reduce its lifespan.

[0003] Undervoltage alarm is an alarm mechanism triggered when the battery voltage is lower than the normal operating threshold. Common causes include battery aging, damage, and insufficient charge. Undervoltage alarm can prevent battery damage due to over-discharge, and even prevent safety accidents. Traditional undervoltage diagnosis strategies usually use a three-stage threshold method, that is, setting three temperature ranges and corresponding three voltage thresholds. When the voltage is lower than the corresponding threshold, the corresponding undervoltage alarm is triggered. However, setting the threshold based on temperature range may result in a large difference in the alarm voltage threshold for temperatures that are close to each other. Such a setting is very unreasonable and may cause false alarms. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, the object of this invention is to provide a battery undervoltage diagnosis and alarm method, system, vehicle, and storage medium.

[0005] This invention proposes a battery undervoltage diagnosis and alarm method, comprising the following steps: determining the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data; detecting the current temperature and current voltage of a single battery cell; determining the target voltage alarm threshold corresponding to the current temperature according to the correspondence; determining whether the single battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, and determining whether the undervoltage type is transient or steady-state undervoltage and the undervoltage level when the undervoltage type is determined to be steady-state undervoltage; triggering the corresponding undervoltage alarm according to the undervoltage level when the undervoltage type is determined to be steady-state undervoltage.

[0006] According to the battery undervoltage diagnosis and alarm method of the present invention, firstly, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Secondly, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, the target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether the battery cell is undervoltage. When it is determined that the battery cell is undervoltage, the undervoltage type is determined to be transient or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, there is a definite and reasonable voltage alarm threshold at each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage. At the same time, a graded alarm is implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation, but also effectively improves the rationality and effectiveness of undervoltage alarm.

[0007] In addition, the battery undervoltage diagnosis and alarm method according to embodiments of the present invention may also have the following additional technical features: Furthermore, determining the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data includes: performing data fitting on the multiple battery temperature data and their corresponding multiple voltage alarm threshold data to obtain a correspondence function between battery temperature and voltage alarm thresholds. In this function, the voltage alarm threshold corresponding to a battery temperature higher than a first preset temperature is the first voltage alarm threshold, and the voltage alarm threshold corresponding to a battery temperature lower than a second preset temperature is the second voltage alarm threshold. The first preset temperature is greater than the second preset temperature, and the first voltage alarm threshold is greater than the second voltage alarm threshold. This allows for accurate determination of the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, facilitating accurate determination of the voltage alarm threshold corresponding to the current temperature, thereby improving the rationality and reliability of undervoltage diagnosis.

[0008] Furthermore, determining whether a battery cell is undervoltage based on the comparison result of the current voltage and the target voltage alarm threshold includes: determining that the battery cell is undervoltage when the current voltage is not greater than the target voltage alarm threshold, otherwise determining that the battery cell is not undervoltage; thus, it can be accurately determined whether a battery cell is undervoltage based on the comparison result of the current voltage and the target voltage alarm threshold, thereby enabling accurate undervoltage diagnosis.

[0009] Furthermore, determining whether the undervoltage type is transient or steady-state when the battery cell experiences undervoltage includes: detecting the current load current of the battery cell when undervoltage occurs; determining the undervoltage type as steady-state undervoltage when the absolute value of the current load current is not greater than a preset current threshold; and starting a delay timer when the absolute value of the current load current is greater than the preset current threshold, continuously detecting the current voltage and the current load current during the delay time, and determining whether the undervoltage type is transient or steady-state undervoltage based on the current voltage and the current load current. This allows for accurate determination of the undervoltage type based on the current load current of the battery cell when undervoltage occurs, thereby avoiding load current interference and helping to ensure the rationality and effectiveness of subsequent undervoltage alarms.

[0010] Furthermore, determining whether the undervoltage type is transient or steady-state undervoltage based on the current voltage and the current load current includes: after the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than the target voltage alarm threshold, determining the undervoltage type as steady-state undervoltage; or, if the current voltage is higher than the target voltage alarm threshold during or after the delay time expires, determining the undervoltage type as transient undervoltage. This allows for accurate determination of whether the undervoltage type is transient or steady-state based on the current voltage and current load current, thereby avoiding load current interference and helping to ensure the rationality and effectiveness of subsequent undervoltage alarms.

[0011] Furthermore, determining the undervoltage level includes: determining the undervoltage level based on the degree to which the current voltage is not greater than the target voltage alarm threshold, wherein the undervoltage level includes at least two levels; triggering the corresponding undervoltage alarm based on the undervoltage level includes: the higher the undervoltage level, the higher the level of the triggered undervoltage alarm, wherein the undervoltage alarm level includes at least two levels, and the undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation; thus, the undervoltage level can be classified according to the degree of undervoltage, and the corresponding alarm level can be determined according to the undervoltage level, so that users can be informed of the undervoltage level in a timely manner and take corresponding actions, which can not only effectively improve the rationality and effectiveness of undervoltage alarms, but also ensure user safety.

[0012] Furthermore, when detecting the current voltage of a battery cell, the method also includes diagnosing battery damage or sampling circuit faults, including: when the current voltage of any battery cell in the battery pack is lower than the average current voltage of other battery cells in the pack, calculating the sum of the current voltages of all battery cells in the pack, and determining the battery voltage of the pack; when the first difference between the sum of the voltages and the battery voltage is less than or equal to a preset difference, determining that the battery cell has a battery damage fault; and sending an alarm message for battery damage; or, when the first difference between the sum of the voltages and the battery voltage is greater than the preset difference, subtracting the current voltage of the battery cell with normal voltage from the current voltage of the battery cell with low voltage, and summing the differences to obtain a voltage difference sum; when the difference between the voltage difference sum and the first difference is less than a first preset difference threshold, determining that the battery cell has a sampling circuit fault; and sending an alarm message for sampling circuit fault. This can effectively detect battery damage or sampling circuit failures. Classifying and diagnosing undervoltage caused by battery damage or sampling circuit failures helps to clarify the cause of the failure, thereby effectively improving the rationality and effectiveness of undervoltage alarms.

[0013] Furthermore, when detecting the current voltage of individual battery cells, the system also includes low battery diagnosis, including: determining the battery pack's charge level when the current voltage of all battery cells in the battery pack is lower than a preset undervoltage threshold, or when the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than a second preset difference threshold; determining the battery pack's low battery level when the charge level is less than a preset charge level threshold; and sending a low battery alarm message. This effectively detects low battery situations, categorizes and diagnoses undervoltage caused by low battery, helps clarify the cause of the fault, and thus effectively improves the rationality and effectiveness of undervoltage alarms.

[0014] Furthermore, if the cause of the undervoltage is determined according to the methods described above and does not fall under any of the aforementioned sampling circuit faults, battery damage faults, or low battery levels, an alarm message for an unknown type of undervoltage fault is sent. Thus, when the cause of the fault cannot be determined and further diagnosis is required, the corresponding alarm message for an unknown type of undervoltage fault is sent for reporting, facilitating further analysis of the fault by relevant personnel.

[0015] Furthermore, after triggering the corresponding undervoltage alarm according to the undervoltage level, the method also includes alarm recovery, including: setting an alarm recovery threshold corresponding to the target voltage alarm threshold, wherein the alarm recovery threshold is greater than the target voltage alarm threshold; after triggering the undervoltage alarm, the undervoltage alarm is only cleared when the current voltage rises from no greater than the target voltage alarm threshold to a value higher than the alarm recovery threshold; thereby, by setting an alarm clearance lower limit and using hysteresis comparison, the frequent alarms caused by voltage oscillations near the alarm value can be effectively reduced, thus effectively reducing the frequency of fault occurrence and clearance, reducing the workload of engineers in troubleshooting after a fault, saving human resources, and reducing operating costs.

[0016] To address the aforementioned problems, this invention also proposes a battery undervoltage diagnosis and alarm system, comprising: a first determining module, used to determine the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data; a detection module, used to detect the current temperature and current voltage of a single battery cell; a second determining module, used to determine a target voltage alarm threshold corresponding to the current temperature according to the correspondence; a diagnosis module, used to determine whether the single battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, and when the single battery cell is determined to be undervoltage, to determine whether the undervoltage type is transient undervoltage or steady-state undervoltage, and to determine the undervoltage level; and an alarm module, used to trigger a corresponding undervoltage alarm according to the undervoltage level when the undervoltage type is determined to be steady-state undervoltage.

[0017] According to the battery undervoltage diagnosis and alarm system of the present invention, the battery undervoltage diagnosis and alarm method of the above embodiment is executed. First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Second, the current temperature and current voltage of the battery cell are detected. Then, according to the correspondence, the target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether the battery cell is undervoltage. When it is determined that the battery cell is undervoltage, the undervoltage type is determined to be transient undervoltage or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, there is a definite and reasonable voltage alarm threshold at each temperature. Undervoltage is determined based on voltage value and voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage. At the same time, a graded alarm is implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation, but also effectively improves the rationality and effectiveness of undervoltage alarm.

[0018] To address the aforementioned problems, the present invention also proposes a vehicle comprising: a battery pack including at least one battery cell; and a battery undervoltage diagnosis and alarm system as described in the second aspect embodiment of the present invention above; or, the vehicle comprising: a battery pack including at least one battery cell; and a processor, a memory, and a battery undervoltage diagnosis and alarm program stored in the memory and executable on the processor, wherein the battery undervoltage diagnosis and alarm program, when executed by the processor, implements the battery undervoltage diagnosis and alarm method as described in the first aspect embodiment of the present invention above.

[0019] According to an embodiment of the present invention, a vehicle is equipped with the battery undervoltage diagnosis and alarm system described in the above embodiment. The battery undervoltage diagnosis and alarm method described in the above embodiment is executed as follows: First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm thresholds is determined. Second, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, a target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether a single battery cell is undervoltage. When it is determined that a single battery cell is undervoltage, the undervoltage type is determined to be transient or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, a corresponding undervoltage alarm is triggered according to the undervoltage level. By determining the correspondence between voltage alarm thresholds and temperature, a reasonable voltage alarm threshold is defined for each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage, and graded alarms are implemented according to the emergency situation. This not only accurately diagnoses battery undervoltage but also effectively improves the rationality and effectiveness of undervoltage alarms.

[0020] To address the aforementioned problems, the present invention also proposes a computer-readable storage medium storing a battery undervoltage diagnosis and alarm program, wherein the battery undervoltage diagnosis and alarm program, when executed by a processor, implements the battery undervoltage diagnosis and alarm method as described in the first aspect embodiment of the present invention.

[0021] According to an embodiment of the present invention, when a battery undervoltage diagnosis and alarm program stored thereon is executed by a processor, the battery undervoltage diagnosis and alarm method of the above embodiment is executed. First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Second, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, the target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether the single battery cell is undervoltage. When it is determined that the single battery cell is undervoltage, the undervoltage type is determined to be transient undervoltage or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, there is a definite and reasonable voltage alarm threshold at each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage. At the same time, a graded alarm is implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation, but also effectively improves the rationality and effectiveness of undervoltage alarm.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a battery undervoltage diagnosis and alarm method according to an embodiment of the present invention; Figure 2 This is a flowchart of a battery undervoltage diagnosis and alarm method according to a specific embodiment of the present invention; Figure 3 This is a flowchart of a battery undervoltage diagnosis and alarm method according to another specific embodiment of the present invention; Figure 4 This is a flowchart of a method for classifying and diagnosing single-cell undervoltage faults according to a specific embodiment of the present invention; Figure 5 This is a structural block diagram of a battery undervoltage diagnosis and alarm system according to an embodiment of the present invention.

[0024] Figure label: 100 - Battery undervoltage diagnosis and alarm system; 110 - First determination module; 120 - Detection module; 130 - Second determination module; 140 - Diagnosis module; 150 - Alarm module. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0026] The following is for reference. Figures 1-5 The present invention describes a battery undervoltage diagnosis and alarm method, system, vehicle, and storage medium according to embodiments thereof. In the following embodiments of the present invention, the vehicle may be either an electric vehicle or a hybrid vehicle.

[0027] Figure 1 This is a flowchart of a battery undervoltage diagnosis and alarm method according to an embodiment of the present invention. Figure 1 As shown, a battery undervoltage diagnosis and alarm method according to an embodiment of the present invention includes the following steps: Step S1: Based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, determine the correspondence between battery temperature and voltage alarm threshold.

[0028] In a specific embodiment, the correspondence between battery temperature and voltage alarm thresholds is determined based on multiple battery temperature data and their corresponding voltage alarm threshold data. Specifically, the multiple battery temperature data and their corresponding voltage alarm threshold data can be obtained by searching existing technologies; for example, the multiple battery temperature data and their corresponding voltage alarm threshold data can be fitted with a function to obtain the correspondence function.

[0029] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the correspondence between battery temperature and voltage alarm threshold is first determined based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, so as to facilitate the subsequent determination of the voltage alarm threshold corresponding to the current temperature according to the correspondence.

[0030] Step S2: Detect the current temperature and current voltage of the battery cell.

[0031] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the current temperature and current voltage of the battery cell are then detected, so as to facilitate the subsequent determination of the voltage alarm threshold based on the current temperature of the battery cell, thereby facilitating the subsequent determination of whether undervoltage has occurred based on the current voltage and the determined voltage alarm threshold.

[0032] Step S3: Determine the target voltage alarm threshold corresponding to the current temperature based on the correspondence.

[0033] In a specific embodiment, the target voltage alarm threshold corresponding to the current temperature is determined based on the correspondence. Specifically, for example, the corresponding target voltage alarm threshold can be obtained by fitting the current temperature input to the correspondence function.

[0034] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the target voltage alarm threshold corresponding to the current temperature is then determined according to the correspondence, that is, the corresponding alarm threshold is accurately determined according to the current temperature of the battery cell, so as to facilitate subsequent determination of whether undervoltage has occurred based on the current voltage and the determined voltage alarm threshold.

[0035] Step S4: Based on the comparison between the current voltage and the target voltage alarm threshold, determine whether the battery cell is undervoltage, and if it is determined that the battery cell is undervoltage, determine whether the undervoltage type is transient or steady-state undervoltage, and determine the undervoltage level.

[0036] In a specific embodiment, based on the comparison between the current voltage and the target voltage alarm threshold, it is determined whether a battery cell is undervoltage, and if it is determined that a battery cell is undervoltage, the undervoltage type is determined to be transient or steady-state, and the undervoltage level is determined. Specifically, for example, if the current voltage is less than the target voltage alarm threshold, it is determined that a battery cell is undervoltage; for example, the undervoltage type can be determined to be transient or steady-state based on the current load current of the battery cell when undervoltage occurs; for example, the undervoltage level can be determined based on the degree of difference between the current voltage and the target voltage alarm threshold.

[0037] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the method determines whether a battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, and determines whether the undervoltage type is transient or steady-state undervoltage and the undervoltage level when it is determined that the battery cell is undervoltage. This allows for accurate determination of whether undervoltage has occurred, as well as determination of the undervoltage type and undervoltage level, facilitating subsequent alarms based on the undervoltage type and undervoltage level.

[0038] Step S5: When the undervoltage type is determined to be steady-state undervoltage, trigger the corresponding undervoltage alarm according to the undervoltage level.

[0039] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level; that is, an alarm is only triggered when there is steady-state undervoltage, and the corresponding undervoltage alarm is triggered according to the undervoltage level, so as not only to avoid false alarms caused by transient undervoltage, but also to accurately understand the undervoltage level of steady-state undervoltage.

[0040] Therefore, the battery undervoltage diagnosis and alarm method according to embodiments of the present invention first determines the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data. Secondly, it detects the current temperature and current voltage of a single battery cell. Then, based on the correspondence, it determines the target voltage alarm threshold corresponding to the current temperature. Next, based on the comparison between the current voltage and the target voltage alarm threshold, it determines whether a single battery cell is undervoltage. When it is determined that a single battery cell is undervoltage, it determines whether the undervoltage type is transient or steady-state, and determines the undervoltage level. Finally, when the undervoltage type is determined to be steady-state undervoltage, it triggers the corresponding undervoltage alarm based on the undervoltage level. By determining the correspondence between voltage alarm thresholds and temperature, a reasonable voltage alarm threshold is established for each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage, and graded alarms are implemented according to the emergency situation. This not only accurately diagnoses battery undervoltage but also effectively improves the rationality and effectiveness of undervoltage alarms.

[0041] In one embodiment of the present invention, step S1 determines the correspondence between battery temperature and voltage alarm threshold based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, including: performing data fitting on the multiple battery temperature data and their corresponding multiple voltage alarm threshold data to obtain a correspondence function between battery temperature and voltage alarm threshold, wherein the voltage alarm threshold corresponding to the battery temperature higher than a first preset temperature in the correspondence function is the first voltage alarm threshold, and the voltage alarm threshold corresponding to the battery temperature lower than a second preset temperature in the correspondence function is the second voltage alarm threshold, wherein the first preset temperature is greater than the second preset temperature, and the first voltage alarm threshold is greater than the second voltage alarm threshold.

[0042] In a specific embodiment, data fitting is performed on multiple battery temperature data and their corresponding voltage alarm threshold data to obtain a correspondence function between battery temperature and voltage alarm threshold. Specifically, tools such as MATLAB can be used for data fitting.

[0043] In a specific embodiment, the voltage changes significantly with temperature within the temperature range from a first preset temperature to a second preset temperature. The voltage alarm threshold set within this temperature range covers all voltage conditions requiring alarm. Therefore, the voltage alarm threshold corresponding to a battery temperature higher than the first preset temperature in the corresponding function can be set as the first voltage alarm threshold, and the voltage alarm threshold corresponding to a battery temperature lower than the second preset temperature in the corresponding function can be set as the second voltage alarm threshold. Specifically, the first preset temperature is greater than the second preset temperature, the first voltage alarm threshold is greater than the second voltage alarm threshold, and the first preset temperature, second preset temperature, first voltage alarm threshold, and second voltage alarm threshold are set as needed.

[0044] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, multiple battery temperature data and their corresponding multiple voltage alarm threshold data are fitted to obtain a correspondence function between battery temperature and voltage alarm threshold. Furthermore, the voltage alarm threshold corresponding to a battery temperature higher than a first preset temperature in the correspondence function is the first voltage alarm threshold, and the voltage alarm threshold corresponding to a battery temperature lower than a second preset temperature in the correspondence function is the second voltage alarm threshold. This allows for accurate determination of the correspondence between battery temperature and voltage alarm threshold based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, facilitating accurate determination of the voltage alarm threshold corresponding to the current temperature in subsequent steps, thereby improving the rationality and reliability of undervoltage diagnosis.

[0045] In one embodiment of the present invention, step S4 determines whether a battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, including: when the current voltage is not greater than the target voltage alarm threshold, it is determined that the battery cell is undervoltage; otherwise, it is determined that the battery cell is not undervoltage.

[0046] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, when the current voltage is not greater than the target voltage alarm threshold, it is determined that the battery cell is undervoltage; otherwise, it is determined that the battery cell is not undervoltage. In this way, based on the comparison result between the current voltage and the target voltage alarm threshold, it is possible to accurately determine whether the battery cell is undervoltage, thereby enabling accurate undervoltage diagnosis.

[0047] In one embodiment of the present invention, step S4, when determining that a battery cell is undervoltage, determines whether the undervoltage type is transient or steady-state, includes: detecting the current load current of the battery cell when undervoltage occurs; when the absolute value of the current load current is not greater than a preset current threshold, determining that the undervoltage type is steady-state; when the absolute value of the current load current is greater than the preset current threshold, starting a delay timer, and continuously detecting the current voltage and current load current during the delay time, and determining whether the undervoltage type is transient or steady-state based on the current voltage and current load current.

[0048] In a specific embodiment, the current load current of a single battery cell is first detected when undervoltage occurs. Then, the undervoltage type is determined to be either transient or steady-state undervoltage based on the current load current. Specifically, when the absolute value of the current load current is not greater than a preset current threshold, the undervoltage type is determined to be steady-state undervoltage; when the absolute value of the current load current is greater than the preset current threshold, a delay timer is started, and the current voltage and current load current are continuously detected during the delay time, and the undervoltage type is determined to be either transient or steady-state undervoltage based on the current voltage and current load current.

[0049] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the current load current of the battery cell is first detected when undervoltage occurs; when the absolute value of the current load current is not greater than a preset current threshold, the undervoltage type is determined to be steady-state undervoltage; when the absolute value of the current load current is greater than the preset current threshold, a delay timer is started, and the current voltage and current load current are continuously detected during the delay time, and the undervoltage type is determined to be transient undervoltage or steady-state undervoltage based on the current voltage and current load current; in this way, the type of undervoltage can be accurately determined based on the current load current of the battery cell when undervoltage occurs, thereby avoiding load current interference and helping to ensure the rationality and effectiveness of subsequent undervoltage alarms.

[0050] In one embodiment of the present invention, determining the undervoltage type as transient undervoltage or steady-state undervoltage based on the current voltage and the current load current includes: after the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than a target voltage alarm threshold, determining the undervoltage type as steady-state undervoltage; or, if the current voltage is higher than the target voltage alarm threshold during or after the delay time expires, determining the undervoltage type as transient undervoltage.

[0051] In a specific embodiment, after the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than a target voltage alarm threshold, the undervoltage type is determined to be steady-state undervoltage; if the current voltage is higher than the target voltage alarm threshold during or after the delay time expires, the undervoltage type is determined to be transient undervoltage. Specifically, the delay time and the target voltage alarm threshold are set as needed.

[0052] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, after the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than a target voltage alarm threshold, the undervoltage type is determined to be steady-state undervoltage; if the current voltage is higher than the target voltage alarm threshold during or after the delay time expires, the undervoltage type is determined to be transient undervoltage. In this way, the undervoltage type can be accurately determined as transient or steady-state undervoltage based on the current voltage and current load current, thereby avoiding load current interference and helping to ensure the rationality and effectiveness of subsequent undervoltage alarms.

[0053] In one embodiment of the present invention, step S4 determines the undervoltage level, including: determining the undervoltage level based on the degree to which the current voltage is not greater than the target voltage alarm threshold, wherein the undervoltage level includes at least two undervoltage levels; step S5 triggers the corresponding undervoltage alarm based on the undervoltage level, including: the higher the undervoltage level, the higher the level of the corresponding undervoltage alarm, wherein the undervoltage alarm level includes at least two undervoltage alarm levels, and the undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation.

[0054] In a specific embodiment, the undervoltage level is determined based on the degree to which the current voltage does not exceed the target voltage alarm threshold. Specifically, the undervoltage level includes at least two levels, for example, three levels: Level 1, Level 2, and Level 3.

[0055] In a specific embodiment, the higher the undervoltage level, the higher the level of the corresponding undervoltage alarm. The specific undervoltage alarm levels include at least two levels, for example, three levels: Level 1, Level 2, and Level 3. The undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation. For example, Level 1 undervoltage alarm only displays an alarm, Level 2 undervoltage alarm limits discharge power to a low degree, and Level 3 undervoltage alarm limits discharge power to a high degree.

[0056] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, the undervoltage level is determined based on the degree to which the current voltage is not greater than the target voltage alarm threshold. The higher the undervoltage level, the higher the level of the corresponding undervoltage alarm. The undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation. In this way, the undervoltage level can be divided into levels, and the corresponding alarm level can be determined according to the undervoltage level, so that users can know the undervoltage level in time and take corresponding actions. This not only effectively improves the rationality and effectiveness of undervoltage alarm, but also ensures user safety.

[0057] In one embodiment of the present invention, when an undervoltage alarm is triggered, the undervoltage can be not classified and diagnosed as described in the above embodiments of the present invention. Instead, an undervoltage alarm of the corresponding level is triggered only when a steady-state undervoltage is determined to occur. That is, only a level 1 undervoltage alarm, a level 2 undervoltage alarm, or a level 3 undervoltage alarm is displayed. This allows users to understand the undervoltage level in a timely manner and take corresponding actions.

[0058] In another embodiment of the present invention, when issuing an undervoltage alarm, not only can a corresponding level of undervoltage alarm be issued upon confirmation of a steady-state undervoltage, i.e., displaying a level 1, level 2, or level 3 undervoltage alarm, but the cause of the undervoltage can also be classified and diagnosed, and a graded alarm can be issued based on the specific undervoltage classification and diagnosis results. That is, while implementing the undervoltage level, the system displays undervoltage classification diagnoses such as battery damage, sampling circuit failure, low battery, or other faults awaiting further determination; this helps to clarify the cause of the fault and provide graded warnings for the fault type, facilitating corresponding repairs or handling. The undervoltage classification diagnosis is described in detail below: In one embodiment of the present invention, step S2, when detecting the current voltage of a battery cell, also includes diagnosing battery damage or sampling circuit failure.

[0059] Specifically, the battery damage fault diagnosis includes: when the current voltage of any battery cell in the battery pack is lower than the average current voltage of other battery cells in the battery pack, calculating the sum of the current voltages of all battery cells in the battery pack, and determining the battery voltage of the battery pack; when the first difference between the sum of voltages and the battery voltage is less than or equal to a preset difference, determining that the battery cell does not have a sampling circuit fault but has a battery damage fault; and sending an alarm message for the battery damage fault.

[0060] Alternatively, the sampling circuit fault diagnosis specifically includes: when the current voltage of any single battery cell in the battery pack is detected to be lower than the average current voltage of other battery cells in the battery pack, calculating the sum of the current voltages of all battery cells in the battery pack, and determining the battery voltage of the battery pack; when the first difference between the sum of voltages and the battery voltage is greater than a preset difference, subtracting the current voltage of the battery cell with normal voltage from the current voltage of the battery cell with low voltage, and summing the differences to obtain the voltage difference sum; when the difference between the voltage difference sum and the first difference is less than a first preset difference threshold, determining that the battery cell has a sampling circuit fault; and sending an alarm message for the sampling circuit fault.

[0061] In step S2, when detecting the current voltage of a battery cell, the method also includes low battery diagnosis, specifically including: when the current voltage of all battery cells in the battery pack is detected to be lower than a preset undervoltage threshold, or when the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than a second preset difference threshold, the battery pack charge is determined; when the charge is less than a preset charge threshold, the battery pack charge is determined to be low; and a low battery alarm message is sent.

[0062] In a specific embodiment, when detecting the current voltage of a battery cell, if the current voltage of any battery cell in the battery pack is lower than the average current voltage of the other battery cells in the pack, the sum of the current voltages of all battery cells in the pack is calculated, and the battery voltage of the pack is determined. If the difference between the sum of voltages and the battery voltage is less than or equal to a preset difference, it is determined that the battery cell does not have a sampling circuit fault but has a battery damage fault, and an alarm message for battery damage fault is sent. Specifically, the preset difference and the first preset difference threshold are set as needed.

[0063] In a specific embodiment, when detecting the current voltage of a battery cell, if the current voltage of any battery cell in the battery pack is lower than the average current voltage of the other battery cells in the pack, the sum of the current voltages of all battery cells in the pack is calculated, and the battery voltage of the pack is determined. If the difference between the sum of voltages and the first difference of the battery voltage is greater than a preset difference, the difference between the current voltage of the battery cell with normal voltage and the current voltage of the battery cell with low voltage (i.e., undervoltage cell) is calculated, and the differences are summed to obtain the voltage difference sum. If the difference between the voltage difference sum and the first difference is less than a first preset difference threshold, it is determined that there is a sampling circuit fault in the battery cell, and an alarm message for the sampling circuit fault is sent. Specifically, the preset difference and the first preset difference threshold are set as needed.

[0064] In a specific embodiment, when detecting the current voltage of a battery cell, if the current voltage of all battery cells in the battery pack is lower than a preset undervoltage threshold, or if the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than a second preset difference threshold, the battery pack's charge level is determined; if the charge level is less than a preset charge level threshold, the battery pack's charge level is determined to be too low; and a low charge level alarm message is sent; the undervoltage threshold, the second preset difference threshold, and the charge level threshold are set as needed.

[0065] Specifically, the battery undervoltage diagnosis and alarm method according to the embodiments of the present invention, when detecting the current voltage of a battery cell, also includes at least one of battery damage fault diagnosis, sampling circuit fault diagnosis, and low power diagnosis.

[0066] The sampling circuit fault diagnosis includes: when the current voltage of any battery cell in the battery pack is lower than the average current voltage of other battery cells in the battery pack, calculating the sum of the current voltages of all battery cells in the battery pack and determining the battery voltage of the battery pack; when the first difference between the sum of voltages and the battery voltage is less than or equal to a preset difference, determining that the battery cell does not have a sampling circuit fault but has a battery damage fault; and sending an alarm message for the battery damage fault.

[0067] On the other hand, when the voltage sum and the first difference between the battery voltage are greater than the preset difference, the current voltage of the battery cell with normal voltage is subtracted from the current voltage of the battery cell with low voltage, and the difference is summed to obtain the voltage difference sum; when the difference between the voltage difference sum and the first difference is less than the first preset difference threshold, it is determined that there is a sampling circuit fault in the battery cell; and an alarm message for the sampling circuit fault is sent.

[0068] On the other hand, when it is detected that the current voltage of all battery cells in the battery pack is lower than the preset undervoltage threshold, or when it is detected that the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than the second preset difference threshold, the battery pack's charge level is determined; when the charge level is less than the preset charge level threshold, the battery pack's charge level is determined to be too low; and an alarm message indicating that the charge level is too low is sent.

[0069] Based on the above, it can effectively detect battery damage, sampling circuit failure, and low power diagnosis. It can classify and diagnose undervoltage caused by low power, battery damage, and sampling circuit failure, which helps to clarify the cause of the failure and thus effectively improve the rationality and effectiveness of undervoltage alarm.

[0070] In one embodiment of the present invention, when the cause of undervoltage determined according to the above-described method does not meet any of the above-mentioned sampling circuit fault, battery damage fault, and low power, an alarm message for an unknown type of undervoltage fault is sent. That is, when none of the above diagnostic conditions are met, the cause of the fault cannot be determined, and further diagnosis is required, a corresponding alarm message for an unknown type of undervoltage fault is sent for reporting, thereby facilitating relevant personnel to further analyze the cause of the fault.

[0071] In one embodiment of the present invention, after triggering the corresponding undervoltage alarm according to the undervoltage level in step S5, the method further includes alarm recovery, including: setting an alarm recovery threshold corresponding to the target voltage alarm threshold, wherein the alarm recovery threshold is greater than the target voltage alarm threshold; after triggering the undervoltage alarm, the undervoltage alarm is cleared only when the current voltage rises from not greater than the target voltage alarm threshold to greater than the alarm recovery threshold.

[0072] In a specific embodiment, after an undervoltage alarm is triggered, the alarm is only cleared when the current voltage rises from below the target voltage alarm threshold to above the alarm recovery threshold. Specifically, the alarm recovery threshold is set according to the target voltage alarm threshold, and the alarm recovery threshold is greater than the target voltage alarm threshold.

[0073] Specifically, according to the battery undervoltage diagnosis and alarm method of the present invention, an alarm recovery threshold corresponding to a target voltage alarm threshold is set, wherein the alarm recovery threshold is greater than the target voltage alarm threshold; after triggering an undervoltage alarm, the undervoltage alarm is only cleared when the current voltage rises from no greater than the target voltage alarm threshold to a value higher than the alarm recovery threshold; thereby, by setting an alarm clearance lower limit and using hysteresis comparison, the frequent alarms caused by voltage oscillations near the alarm value can be effectively reduced, thereby effectively reducing the frequency of fault occurrence and clearance, reducing the workload of engineers in troubleshooting after a fault, saving human resources, and reducing operating costs.

[0074] The battery undervoltage diagnosis and alarm method of the present invention will be further described below with reference to specific embodiments. In this specific embodiment, a battery undervoltage diagnosis and alarm method is provided.

[0075] Figure 2 This is a flowchart of a battery undervoltage diagnosis and alarm method according to a specific embodiment of the present invention, such as... Figure 2 As shown in this specific embodiment, the battery undervoltage diagnosis and alarm method includes: Step S10: Determine the undervoltage alarm threshold.

[0076] Step S20: Tiered alarm and recovery.

[0077] In this specific embodiment, since the voltage of a single cell is affected by temperature, an increase in internal resistance at low temperatures will cause a voltage drop. Therefore, the undervoltage alarm threshold... It shouldn't be a fixed value, but rather a threshold determined by temperature. Currently, the setting of alarm thresholds is rather crude. Generally, several temperature ranges are set, and within each temperature range, there is only one alarm threshold. This makes the alarm threshold setting inaccurate. For example, if (-10℃, 0℃) is a temperature range, the alarm threshold is 1.7V, and if (0℃, 10℃) is a temperature range, the alarm threshold is 2.8V. This leads to a problem where the temperature critical alarm threshold is set unreasonably. For instance, 0.1℃ and -0.1℃ are actually very close temperatures, but the alarm thresholds are 2.8V and 1.7V respectively, a difference of 1.1V.

[0078] Therefore, S10 determines the undervoltage alarm threshold by: proposing a temperature-voltage threshold function. Based on existing temperature and voltage alarm threshold data: A temperature-alarm threshold function is generated through fitting. Specifically, for example, when T ≤ 10°C, =2.8V; when T≤0℃, =2.2V; T≤-10°C, =1.7V; By fitting the two sets of temperature and voltage values ​​x=[-10 0 10]; y=[1.7 2.2 2.8] into the Curve Fitting Tool in MATLAB, an approximate function of the temperature-voltage threshold can be obtained. This allows us to determine the undervoltage alarm threshold that should be set at different temperatures.

[0079] Specifically, in ( Within this temperature range, voltage changes significantly with temperature. The voltage alarm threshold set within this temperature range covers all voltage conditions requiring alarm. Therefore, when the temperature... The voltage alarm threshold will no longer increase; it will all be set to [value missing]. When the temperature The voltage alarm threshold will no longer decrease, and will be set to [value]. .

[0080] In this specific embodiment, step S30, graded alarm and recovery, includes: step S31: graded alarm; step S32: alarm threshold determination; step S33: warning mode determination; step S34: hysteresis comparison.

[0081] In this specific embodiment, step S31, the graded alarm, includes: to further differentiate and process alarms, alarms are divided into Level 1 alarms, Level 2 alarms, and Level 3 alarms. Specifically, a Level 1 alarm indicates a low voltage level and primarily serves as a warning to the user; under the same temperature conditions, if the voltage drops even lower, the low voltage situation is more severe, triggering a Level 2 alarm to prompt the user to take immediate corrective action; when the battery voltage drops to extremely low levels, the low voltage situation is most severe, triggering a Level 3 alarm to prompt the user to take immediate corrective action.

[0082] In this specific embodiment, step S32, determining the alarm threshold, includes: T≤T1, =U1;T≤T2, =U2;T≤T3, =U3, and the function determined therefrom. This can be used as a method for determining a Level 1 alarm; T≤T1, =U4;T≤T2, =U5;T≤T3 =U6, and the function determined therefrom. As a method for determining a level 2 alarm; T≤T1, =U7;T≤T2, =U8;T≤T3, =U9, and the function determined therefrom. This serves as a method for determining a Level 3 alarm.

[0083] In this specific embodiment, step S33, determining the warning method, includes: Level 1 warning: displaying a yellow warning icon and text on the instrument panel to inform the driver "low battery, please charge in time" or "limited output"; Level 2 warning: the BMS actively "reduces power", gradually limiting the maximum discharge power to 70%, 50%, etc., so that the driver can feel the power weakening, but has enough time to safely drive off the main road for maintenance or recharging; Level 3 warning: the BMS actively "reduces power", gradually limiting the maximum discharge power to 20%, 10%, etc., making the vehicle difficult to use normally, prompting the user to immediately carry out maintenance or recharge.

[0084] In this specific embodiment, step S34, hysteresis comparison, includes: to prevent frequent alarm state transitions caused by voltage fluctuations near a threshold, hysteresis comparison is used. Specifically, an alarm recovery threshold is set. ,and ,For example, It is 2.8V. The voltage is set to 3.0V. The undervoltage alarm will only be cleared when the voltage rises from below 2.8V to above 3.0V. This effectively reduces frequent alarms caused by voltage oscillations around the alarm value.

[0085] Figure 3 This is a flowchart of a battery undervoltage diagnosis and alarm method according to another specific embodiment of the present invention, such as... Figure 3 As shown in this specific embodiment, the battery undervoltage diagnosis and alarm method includes: Step S10: Determine the undervoltage alarm threshold.

[0086] Step S20: Fault diagnosis.

[0087] Step S30: Tiered alarm and recovery.

[0088] In this specific embodiment, compared with the battery undervoltage diagnosis and alarm method provided in the above specific embodiment, the battery undervoltage diagnosis and alarm method adds a step S20 fault diagnosis between step S10 determining the undervoltage alarm threshold and step S30 graded alarm and recovery. Step S10 determining the undervoltage alarm threshold and step S30 graded alarm and recovery in the battery undervoltage diagnosis and alarm method in this specific embodiment are similar to step S10 determining the undervoltage alarm threshold and step S30 graded alarm and recovery in the battery undervoltage diagnosis and alarm method in the above specific embodiment. For details, please refer to the above specific embodiment, which will not be repeated here. Only the fault diagnosis of step S20 will be explained.

[0089] In this specific embodiment, the fault diagnosis in step S20 includes: step S21: load current interference diagnosis; step S22: low battery power diagnosis; step S23: sampling circuit fault diagnosis.

[0090] In this specific embodiment, S21 load current interference diagnosis includes: instantaneous voltage drops caused by high current conditions such as startup and acceleration, which can lead to false alarms. Therefore, when determining undervoltage, a current parameter is introduced to distinguish between transient undervoltage and steady-state undervoltage. When the voltage is detected to be below the dynamic threshold... Immediately determine the absolute value of the current load current. Is it greater than a set value? Specifically, if If the voltage drop is due to a high-current load, it is assumed to be a transient voltage drop and no alarm is immediately triggered. Instead, a variable delay timer is activated. , It can be set to a fixed value (e.g., 3-5 seconds). If the current drops to the set current threshold after the delay, the delay will be lifted. the following( ), while the voltage is still lower than If the voltage rises above the threshold during the delay period, the alarm flag is cleared.

[0091] In this specific embodiment, the low battery diagnosis of S22 includes: checking the voltage of all individual cells; if all individual cell voltages are lower than the undervoltage threshold or the difference between the highest individual cell voltage and the undervoltage threshold is not large (highest individual cell voltage - undervoltage threshold < ... , (Values ​​can be flexibly set according to actual needs), which is considered as all individual cell voltages being low; if all individual cell voltages are low, determine whether it is caused by low battery power: Currently ( It can be flexibly set according to actual needs. Generally, the low voltage alarm is triggered by low battery power (the actual battery power may be 0%, so the SOC threshold can be set to a small value). The reason for the low voltage alarm is: the battery power is too low.

[0092] In this specific embodiment, the fault diagnosis of the S23 sampling circuit includes: if the voltage of an individual cell is too low while the voltages of the remaining cells are normal, then it is determined whether the low voltage value is caused by a sampling fault. The cumulative voltage value (i.e., the sum of all cell voltage values ​​collected by the BMS (BATTERYMANAGEMENT SYSTEM)) is calculated and compared with the total battery voltage (the battery voltage signal collected by the BMS). If the total battery voltage is close to the nominal voltage, and the cumulative voltage value is close to the total battery voltage (i.e.,...), then... This proves that the sampling is fault-free and the low voltage alarm for a single cell is true. The reason for the low voltage alarm is: battery damage or fault, such as damage to the battery pack / cell, water ingress, etc.

[0093] If the cumulative voltage value is very large compared to the total battery voltage difference (i.e.) If a single-cell sampling failure exists, calculate the pressure difference between the undervoltage cell and the normal cell, and sum the pressure differences to obtain the total pressure difference. (It should be noted that since the normal cell voltages are relatively close, any normal cell voltage can be selected for comparison. In this embodiment, the voltage of the normal cell preceding the first undervoltage cell is selected as the normal value, and the difference between each normal cell voltage and the undervoltage cell voltage value is calculated and summed.) If the voltage difference and (Cumulative voltage value - Total battery voltage = (Approaching, that is) ,in, The fact that the values ​​were flexibly set according to actual needs further verified that the problem was caused by a single-unit sampling failure, and the reason for the undervoltage report was: sampling failure.

[0094] The following explanation, in conjunction with the classification and diagnosis method for single-cell undervoltage faults, further explains the battery undervoltage diagnosis and alarm method provided in the above specific embodiments.

[0095] Figure 4 This is a flowchart of a method for classifying and diagnosing single-cell undervoltage faults according to a specific embodiment of the present invention, such as... Figure 4 As shown in this specific embodiment, the method for classifying and diagnosing the undervoltage fault of this single cell includes the following steps: S11: The BMS system alarms for undervoltage of individual battery cells. When the lowest cell voltage is lower than the preset alarm voltage value, it reports a cell undervoltage fault and initiates the undervoltage classification and diagnosis process.

[0096] S12: Determine if all individual cell voltages are low. Specifically, the method is as follows: Check the voltage of all individual cells. If all individual cell voltages are below the undervoltage threshold, or if the difference between the highest individual cell voltage and the undervoltage threshold is not significant (highest individual cell voltage - undervoltage threshold < ... , (The value can be flexibly set according to actual needs), which is considered to mean that the voltage of all individual cells is low.

[0097] S13: If all individual cell voltages are low, determine if it's caused by low battery power. Specifically, the determination method is: Currently... ( It can be flexibly set according to actual needs. Generally, the low voltage alarm is triggered by low battery power (the actual battery power may be 0%, so the SOC threshold can be set to a small value). The reason for the low voltage alarm is: the battery power is too low.

[0098] S14: If the voltage of an individual cell is too low while the voltages of the others are normal, determine whether the low voltage is due to a sampling fault. Specifically, calculate the cumulative voltage value (i.e., the sum of all cell voltage values ​​collected by the BMS), compare it with the total battery voltage (the battery voltage signal collected by the BMS), and if the total battery voltage is close to the nominal voltage (excluding a battery voltage collection fault), and the cumulative voltage value is close to the total battery voltage... , The values ​​can be flexibly set according to actual needs, proving that the sampling is fault-free and the single-cell undervoltage alarm is true. The reason for the undervoltage alarm is: battery damage, such as damage to the battery pack / cell, water ingress, etc.

[0099] S15: If the cumulative voltage value is very large compared to the total battery voltage difference ( If the voltage difference is found to be between the under-voltage and normal cells, then it is determined whether the problem is caused by a single-cell sampling failure. Specifically, the voltage difference between the under-voltage cell and the normal cell is calculated and summed to obtain the voltage difference sum. If the pressure difference and (Cumulative voltage - Total battery voltage = Approaching (i.e.) , This further confirms that the problem was caused by a single-unit sampling failure, and the reason for the undervoltage report is: sampling failure.

[0100] S16: If the diagnostic results of S12, S13, S14, and S15 are not met and the cause of the fault cannot be determined, report: Unknown type undervoltage fault. Then send the corresponding unknown type undervoltage fault alarm information for reporting, so that relevant personnel can further analyze the cause of the fault.

[0101] That is, the battery undervoltage diagnosis and alarm method provided in this specific embodiment first determines the undervoltage voltage threshold based on the obtained relationship between temperature and voltage; then, it determines whether there is undervoltage based on the undervoltage voltage threshold and determines the undervoltage level, while determining whether the undervoltage is steady-state or transient (i.e., eliminating load current interference). If it is steady-state undervoltage, an alarm is issued; otherwise, no alarm is issued. Next, in the case of steady-state undervoltage, it further distinguishes between low power, sampling fault / battery damage, and other faults based on the individual cell voltage. Power is not limited for sampling faults, but power is limited for low power, battery damage, and other faults that require immediate power replenishment or inspection. Finally, it continuously monitors and clears the alarm when the conditions are met.

[0102] As can be seen, the battery undervoltage diagnosis and alarm method provided in the above specific embodiments refines the undervoltage alarm threshold by setting a temperature-undervoltage threshold function, which can set a more reasonable undervoltage alarm threshold for different temperatures. In the case of high current interference, when a high current is detected causing undervoltage, a delay timer is set to wait for a period of time until the current returns to normal before judging whether the voltage is still lower than the set value. When undervoltage is caused by an open circuit in the sampling line, an open circuit alarm is triggered to prompt engineers to comprehensively consider sampling faults and undervoltage issues.

[0103] Therefore, the battery undervoltage diagnosis and alarm method provided in the above specific embodiments has the following significant advantages compared with the prior art: 1. The undervoltage alarm threshold is determined as a function of temperature, and there is a definite and reasonable alarm voltage threshold at each temperature, making the alarm more reasonable and effective; 2. The undervoltage situation is further subdivided, and graded alarms are implemented according to the emergency situation, effectively improving the effectiveness of the alarm; 3. The voltage drop caused by large load current is taken into consideration, effectively reducing false alarms; 4. Undervoltage caused by low power and acquisition circuit failure is classified and alarmed, clarifying the cause of the fault and reducing user panic; 5. An alarm cancellation lower limit is set, and the frequency of fault occurrence and cancellation is reduced through hysteresis comparison, reducing the workload of engineers in troubleshooting after the fault, saving human resources, and reducing operating costs.

[0104] In summary, the battery undervoltage diagnosis and alarm method according to embodiments of the present invention first determines the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data. Second, it detects the current temperature and current voltage of a single battery cell. Then, based on the correspondence, it determines the target voltage alarm threshold corresponding to the current temperature. Next, based on the comparison between the current voltage and the target voltage alarm threshold, it determines whether a single battery cell is undervoltage. When it is determined that a single battery cell is undervoltage, it determines whether the undervoltage type is transient or steady-state, and determines the undervoltage level. Finally, when the undervoltage type is determined to be steady-state undervoltage, it triggers the corresponding undervoltage alarm based on the undervoltage level. By determining the correspondence between voltage alarm thresholds and temperature, a reasonable voltage alarm threshold is established for each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage, and graded alarms are implemented according to the emergency situation. This not only accurately diagnoses battery undervoltage but also effectively improves the rationality and effectiveness of undervoltage alarms.

[0105] A further embodiment of the present invention discloses a battery undervoltage diagnosis and alarm system. Figure 5 This is a structural block diagram of a battery undervoltage diagnosis and alarm system according to an embodiment of the present invention, as shown below. Figure 5 As shown, the battery undervoltage diagnosis and alarm system 100 includes: a first determination module 110, a detection module 120, a second determination module 130, a diagnosis module 140, and an alarm module 150.

[0106] Specifically, the first determining module 110 is used to determine the correspondence between battery temperature and voltage alarm threshold based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data; the detection module 120 is used to detect the current temperature and current voltage of a single battery cell; the second determining module 130 is used to determine the target voltage alarm threshold corresponding to the current temperature according to the correspondence; the diagnosis module 140 is used to determine whether a single battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, and when determining the single battery cell, to determine whether the undervoltage type is transient undervoltage or steady-state undervoltage, and to determine the undervoltage level; the alarm module 150 is used to trigger the corresponding undervoltage alarm according to the undervoltage level when the undervoltage type is determined to be steady-state undervoltage.

[0107] In one embodiment of the present invention, the first determining module 110 determines the correspondence between battery temperature and voltage alarm threshold based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, including: performing data fitting on the multiple battery temperature data and their corresponding multiple voltage alarm threshold data to obtain a correspondence function between battery temperature and voltage alarm threshold, wherein the voltage alarm threshold corresponding to the battery temperature higher than a first preset temperature in the correspondence function is the first voltage alarm threshold, and the voltage alarm threshold corresponding to the battery temperature lower than a second preset temperature in the correspondence function is the second voltage alarm threshold, wherein the first preset temperature is greater than the second preset temperature, and the first voltage alarm threshold is greater than the second voltage alarm threshold.

[0108] In one embodiment of the present invention, the diagnostic module 140 determines whether a battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, including: determining that the battery cell is undervoltage when the current voltage is not greater than the target voltage alarm threshold, otherwise determining that the battery cell is not undervoltage.

[0109] In one embodiment of the present invention, the diagnostic module 140 determines whether the undervoltage type is transient or steady-state when it determines that an undervoltage occurs in a battery cell, including: detecting the current load current of the battery cell when the undervoltage occurs; determining that the undervoltage type is steady-state when the absolute value of the current load current is not greater than a preset current threshold; and starting a delay timer when the absolute value of the current load current is greater than the preset current threshold, continuously detecting the current voltage and the current load current during the delay time, and determining whether the undervoltage type is transient or steady-state based on the current voltage and the current load current.

[0110] In one embodiment of the present invention, the diagnostic module 140 determines the undervoltage type as transient undervoltage or steady-state undervoltage based on the current voltage and the current load current, including: after the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than a target voltage alarm threshold, the undervoltage type is determined to be steady-state undervoltage; or, if the current voltage is higher than the target voltage alarm threshold during or after the delay time expires, the undervoltage type is determined to be transient undervoltage.

[0111] In one embodiment of the present invention, the diagnostic module 140 determines the undervoltage level by: determining the undervoltage level based on the degree to which the current voltage is not greater than the target voltage alarm threshold, wherein the undervoltage level includes at least two undervoltage levels; the alarm module 150 triggers a corresponding undervoltage alarm based on the undervoltage level, including: the higher the undervoltage level, the higher the level of the corresponding undervoltage alarm, wherein the undervoltage alarm level includes at least two undervoltage alarm levels, and the undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation.

[0112] In one embodiment of the present invention, when detecting the current voltage of a battery cell, the detection module 120 is also used to diagnose battery damage or sampling circuit faults.

[0113] Specifically, the battery damage fault diagnosis includes: when the current voltage of any battery cell in the battery pack is lower than the average current voltage of other battery cells in the battery pack, calculating the sum of the current voltages of all battery cells in the battery pack, and determining the battery voltage of the battery pack; when the first difference between the sum of voltages and the battery voltage is less than or equal to a preset difference, determining that the battery cell does not have a sampling circuit fault but has a battery damage fault; and sending an alarm message for the battery damage fault.

[0114] Alternatively, the sampling circuit fault diagnosis specifically includes: when the current voltage of any single battery cell in the battery pack is detected to be lower than the average current voltage of other battery cells in the battery pack, the sum of the current voltages of all battery cells in the battery pack is calculated, and the battery voltage of the battery pack is determined; when the first difference between the sum of voltages and the battery voltage is greater than a preset difference, the difference between the current voltage of the battery cell with normal voltage and the current voltage of the battery cell with low voltage is calculated, and the differences are accumulated to obtain the voltage difference sum; when the difference between the voltage difference sum and the first difference is less than a first preset difference threshold, it is determined that there is a sampling circuit fault in the battery cell; and an alarm message for the sampling circuit fault is sent.

[0115] In one embodiment of the present invention, when detecting the current voltage of a battery cell, the detection module 120 is further configured to perform low battery diagnosis, specifically including: when it is detected that the current voltage of all battery cells in the battery pack is lower than a preset undervoltage threshold, or when it is detected that the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than a second preset difference threshold, determining the battery pack's charge capacity; when the charge capacity is less than a preset charge capacity threshold, determining that the battery pack's charge capacity is too low; and sending a low battery alarm message.

[0116] In one embodiment of the present invention, after triggering a corresponding undervoltage alarm according to the undervoltage level, the alarm module 150 is further used for alarm recovery, including: setting an alarm recovery threshold corresponding to a target voltage alarm threshold, wherein the alarm recovery threshold is greater than the target voltage alarm threshold; after triggering the undervoltage alarm, the undervoltage alarm is cleared only when the current voltage rises from not greater than the target voltage alarm threshold to greater than the alarm recovery threshold.

[0117] The battery undervoltage diagnosis and alarm system 100 according to an embodiment of the present invention executes the battery undervoltage diagnosis and alarm method of the above embodiment. First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Second, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, the target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether the single battery cell is undervoltage. When it is determined that the single battery cell is undervoltage, the undervoltage type is determined to be transient undervoltage or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, there is a definite and reasonable voltage alarm threshold at each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage. At the same time, a graded alarm is implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation, but also effectively improves the rationality and effectiveness of undervoltage alarm.

[0118] A further embodiment of the present invention also discloses a vehicle.

[0119] In some embodiments, the vehicle includes: a battery pack including at least one battery cell; and a battery undervoltage diagnosis and alarm system 100 as described in any of the above embodiments of the present invention.

[0120] In other embodiments, the vehicle includes: a battery pack including at least one battery cell; and a processor, a memory, and a battery undervoltage diagnosis and alarm program stored in the memory and executable on the processor, wherein the battery undervoltage diagnosis and alarm program, when executed by the processor, implements the battery undervoltage diagnosis and alarm method as described in any of the above embodiments of the present invention.

[0121] In a specific embodiment, the vehicle can be either an electric vehicle or a hybrid vehicle.

[0122] According to an embodiment of the present invention, a vehicle equipped with a battery undervoltage diagnosis and alarm system 100 as described in the above embodiments executes the battery undervoltage diagnosis and alarm method described in the above embodiments. First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Second, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, a target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether a single battery cell is undervoltage. When it is determined that a single battery cell is undervoltage, the undervoltage type is determined to be transient or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, a corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, a definite and reasonable voltage alarm threshold is provided for each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage, and graded alarms are implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation but also effectively improves the rationality and effectiveness of undervoltage alarms.

[0123] A further embodiment of the present invention discloses a computer-readable storage medium storing a battery undervoltage diagnosis and alarm program, which, when executed by a processor, implements the battery undervoltage diagnosis and alarm method as described in any of the above embodiments of the present invention.

[0124] According to an embodiment of the present invention, when a battery undervoltage diagnosis and alarm program stored thereon is executed by a processor, the battery undervoltage diagnosis and alarm method of the above embodiment is executed. First, based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Second, the current temperature and current voltage of a single battery cell are detected. Then, according to the correspondence, the target voltage alarm threshold corresponding to the current temperature is determined. Next, based on the comparison result between the current voltage and the target voltage alarm threshold, it is determined whether the single battery cell is undervoltage. When it is determined that the single battery cell is undervoltage, the undervoltage type is determined to be transient undervoltage or steady-state undervoltage, and the undervoltage level is determined. Finally, when the undervoltage type is determined to be steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level. In this way, by determining the correspondence between voltage alarm threshold and temperature, there is a definite and reasonable voltage alarm threshold at each temperature. Undervoltage is determined based on the voltage value and the voltage alarm threshold, and the undervoltage situation is further subdivided. An alarm is only triggered in steady-state undervoltage. At the same time, a graded alarm is implemented according to the emergency situation. This not only accurately diagnoses the battery undervoltage situation, but also effectively improves the rationality and effectiveness of undervoltage alarm.

[0125] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0126] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for diagnosing and alarming undervoltage of a battery, characterized in that, Includes the following steps: Based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data, the correspondence between battery temperature and voltage alarm threshold is determined. Detect the current temperature and voltage of each battery cell; Based on the correspondence, determine the target voltage alarm threshold corresponding to the current temperature; Based on the comparison between the current voltage and the target voltage alarm threshold, it is determined whether the battery cell is undervoltage, and when it is determined that the battery cell is undervoltage, it is determined whether the undervoltage type is transient undervoltage or steady-state undervoltage, and the undervoltage level is determined. When the undervoltage type is determined to be the steady-state undervoltage, the corresponding undervoltage alarm is triggered according to the undervoltage level.

2. The battery undervoltage diagnosis and alarm method according to claim 1, characterized in that, The process of determining the correspondence between battery temperature and voltage alarm thresholds based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data includes: Data fitting is performed on multiple battery temperature data and their corresponding multiple voltage alarm threshold data to obtain a correspondence function between battery temperature and voltage alarm threshold. In the correspondence function, the voltage alarm threshold corresponding to the battery temperature higher than a first preset temperature is the first voltage alarm threshold, and the voltage alarm threshold corresponding to the battery temperature lower than a second preset temperature is the second voltage alarm threshold. The first preset temperature is greater than the second preset temperature, and the first voltage alarm threshold is greater than the second voltage alarm threshold.

3. The battery undervoltage diagnosis and alarm method according to claim 1, characterized in that, When detecting the current voltage of a single battery cell, the system also includes diagnosing battery damage or sampling circuit malfunctions, including: When it is detected that the current voltage of any single battery cell in the battery pack is lower than the average current voltage of the other battery cells in the battery pack, the sum of the current voltages of all battery cells in the battery pack is calculated, and the battery voltage of the battery pack is determined. When the voltage and the first difference between the voltage and the battery voltage are less than or equal to a preset difference, it is determined that the battery cell has a battery damage fault. Send an alarm message indicating battery damage or malfunction; Alternatively, when the voltage sum and the first difference between the battery voltage are greater than the preset difference, the current voltage of the battery cell with normal voltage is subtracted from the current voltage of the battery cell with low voltage, and the differences are summed to obtain the voltage difference sum. When the difference between the differential pressure and the first difference is less than a first preset difference threshold, it is determined that the sampling circuit of the battery cell is faulty. Send an alarm message indicating a sampling circuit failure.

4. The battery undervoltage diagnosis and alarm method according to claim 1 or 3, characterized in that, The system also includes low battery diagnostics when detecting the current voltage of individual battery cells, including: When it is detected that the current voltage of all battery cells in the battery pack is lower than a preset undervoltage threshold, or when it is detected that the difference between the highest current voltage of all battery cells in the battery pack and the undervoltage threshold is less than a second preset difference threshold, the charge capacity of the battery pack is determined. When the charge level is less than a preset charge level threshold, it is determined that the battery pack has too low a charge level. Send an alarm message indicating that the battery is too low.

5. The battery undervoltage diagnosis and alarm method according to claim 1, characterized in that, The step of determining whether the undervoltage type is transient or steady-state undervoltage when the battery cell is found to be undervoltage includes: Detect the current load current of the battery cell when undervoltage occurs; When the absolute value of the current load current is not greater than the preset current threshold, the undervoltage type is determined to be the steady-state undervoltage. When the absolute value of the current load current is greater than the preset current threshold, a delay timer is started, and the current voltage and the current load current are continuously detected during the delay time. Based on the current voltage and the current load current, the undervoltage type is determined to be either transient undervoltage or steady-state undervoltage.

6. The battery undervoltage diagnosis and alarm method according to claim 5, characterized in that, The step of determining whether the undervoltage type is transient or steady-state undervoltage based on the current voltage and the current load current includes: After the delay time expires, if the absolute value of the current load current is lower than a preset recovery current threshold and the current voltage is lower than the target voltage alarm threshold, the undervoltage type is determined to be steady-state undervoltage; or, If the current voltage is higher than the target voltage alarm threshold during or after the delay period, the undervoltage type is determined to be transient undervoltage.

7. The battery undervoltage diagnosis and alarm method according to claim 1, characterized in that, Determining the undervoltage level includes: The undervoltage level is determined based on the degree to which the current voltage is not greater than the target voltage alarm threshold, wherein the undervoltage level includes at least two undervoltage levels; The step of triggering a corresponding undervoltage alarm based on the undervoltage level includes: The higher the undervoltage level, the higher the level of the corresponding undervoltage alarm. The undervoltage alarm level includes at least two levels, and the undervoltage alarm includes different levels of alarm display and / or different degrees of discharge power limitation.

8. The battery undervoltage diagnosis and alarm method according to claim 1, characterized in that, After triggering the corresponding undervoltage alarm based on the undervoltage level, the system also includes alarm recovery, including: Set an alarm recovery threshold corresponding to the target voltage alarm threshold, wherein the alarm recovery threshold is greater than the target voltage alarm threshold; After the undervoltage alarm is triggered, the undervoltage alarm will only be cleared when the current voltage rises from no greater than the target voltage alarm threshold to a level higher than the alarm recovery threshold.

9. A battery undervoltage diagnosis and alarm system, characterized in that, include: The first determining module is used to determine the correspondence between battery temperature and voltage alarm threshold based on multiple battery temperature data and their corresponding multiple voltage alarm threshold data. The detection module is used to detect the current temperature and current voltage of the battery cells. The second determining module is used to determine the target voltage alarm threshold corresponding to the current temperature based on the correspondence. The diagnostic module is used to determine whether the battery cell is undervoltage based on the comparison result between the current voltage and the target voltage alarm threshold, and when it is determined that the battery cell is undervoltage, to determine whether the undervoltage type is transient undervoltage or steady-state undervoltage, and to determine the undervoltage level. The alarm module is used to trigger a corresponding undervoltage alarm based on the undervoltage level when the undervoltage type is determined to be the steady-state undervoltage.

10. A vehicle, characterized in that, include: A battery pack, comprising at least one battery cell; and, The battery undervoltage diagnosis and alarm system as described in claim 9; or, A processor, a memory, and a battery undervoltage diagnosis and alarm program stored in the memory and executable on the processor, wherein the battery undervoltage diagnosis and alarm program, when executed by the processor, implements the battery undervoltage diagnosis and alarm method as described in any one of claims 1-8.

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