Vehicle undervoltage fault reason analysis method and system and vehicle

Abstract

The invention discloses a vehicle under-voltage fault reason analysis method and system and a vehicle, and the method comprises the steps: when a vehicle under-voltage fault occurs and the vehicle is in an OFF gear, the vehicle under-voltage fault is analyzed based on the software flashing condition of the vehicle, the wake-up reason and time length of each controller, the high-voltage state of the whole vehicle, the parameters of a power battery and the working state of DCDC; determining the cause of the under-voltage fault of the vehicle; and when the vehicle undervoltage fault occurs and the vehicle is in an ON gear, determining the cause of the vehicle undervoltage fault based on the DCDC working state of the vehicle, the power battery parameters, the vehicle type and the vehicle speed. According to the method, the fault processing time efficiency of the maintenance station can be improved, the time consumption of fault problem analysis by engineers is reduced, the after-sales cost and the labor cost are reduced, and meanwhile, beneficial reference can be provided for function scheme optimization.

Description

Technical Field

[0001] The present invention relates to an automotive control system, and particularly to a method and system for analyzing the causes of vehicle under-voltage faults and a vehicle. Background Art

[0002] With the in-depth development of the electrification, intelligence, and networking of new energy vehicles, different from the usage of traditional fuel vehicles, more and more controller modules of new energy vehicles still need to work after the OFF gear, resulting in an increasing risk of under-voltage faults in new energy vehicle models as the intelligent functions increase. The factors causing under-voltage faults are becoming more and more complex, and the difficulty of troubleshooting problems has increased sharply. In the prior art, for vehicle owners whose vehicles have already had under-voltage faults, they usually jump-start the vehicle by themselves or contact the 4S store for jump-starting, and do not further analyze the causes of the under-voltage faults. At the same time, due to the complexity of the causes of under-voltage faults, the 4S store does not have the ability to analyze and troubleshoot. If the root cause is to be investigated, it is necessary to contact the manufacturer to arrange engineers to go to the site for handling, which undoubtedly increases a large amount of after-sales cost and time cost. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method and system for analyzing the causes of vehicle under-voltage faults and a vehicle, which can improve the efficiency of fault handling in the repair station, reduce the time consumption of engineers for analyzing fault problems, reduce after-sales cost and labor cost, and at the same time can provide a useful reference for optimizing the function scheme.

[0004] A method for analyzing the causes of vehicle under-voltage faults in the present invention includes: When a vehicle under-voltage fault occurs and the vehicle is in the OFF gear, based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state, determine the cause of the vehicle under-voltage fault; When a vehicle under-voltage fault occurs and the vehicle is in the ON gear, based on the DCDC working state of the vehicle, the power battery parameters, the vehicle type, and the vehicle speed, determine the cause of the vehicle under-voltage fault.

[0005] Further, determining the cause of the vehicle under-voltage fault based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state includes: Judge whether there is power loss during the software flashing process. If the judgment is yes, determine that the cause of the vehicle under-voltage fault is power loss during the software flashing process; if the judgment is no, based on the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state, determine the cause of the vehicle under-voltage fault.

[0006] Further, determining the cause of the vehicle undervoltage fault based on the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state includes: If the DCDC output voltage is U1 for a duration not less than T1, obtain the time point T when the DCDC output voltage drops from U1 to U2. f1 Wherein, U1 refers to the DCDC output voltage when the high voltage is applied, and U2 refers to the DCDC output voltage when the high voltage is removed. If the vehicle is in the ON gear for a duration not less than the preset threshold T2, obtain the time point T when the vehicle exits the ON gear. f2 ; Obtain the time point T when the undervoltage fault occurs. 欠压 , and calculate the voltage change time interval T f11 =∣T 欠压 -T f1 ∣ and T f22 =∣T 欠压 -T f2 ∣; If T f11 is less than the preset threshold T3 or T f22 is less than the preset threshold T4, determine that the cause of the vehicle undervoltage fault is the performance attenuation or damage of the battery. If T f11 > the preset threshold T5 or T f22 > the preset threshold T5, determine that the cause of the vehicle undervoltage fault is the vehicle has been parked for a long time.

[0007] Further, determining the cause of the vehicle undervoltage fault based on the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state further includes: Based on the wake-up reasons and durations of each controller, determine whether there is a controller with a wake-up reason exceeding the expected duration. If so, determine the corresponding cause of the vehicle undervoltage fault according to the wake-up reason exceeding the expected duration; if not, determine whether the vehicle has removed the high voltage. When the vehicle is not in the high-voltage removed state, based on the vehicle type and the power battery power, determine that the cause of the vehicle undervoltage fault is low power or the DCDC is not working properly. When the vehicle is in the high-voltage removed state, if the DCDC output voltage is U1 for a duration less than T1, obtain the time point T when the DCDC output voltage drops from U1 to U2. f3 , and obtain the time point T when the undervoltage fault occurs. 欠压 , and calculate the voltage change time interval T f33 =∣T 欠压 -T f3 ∣. If T f33 > the preset threshold T5, determine that the cause of the vehicle undervoltage fault is the vehicle has been parked for a long time.

[0008] Further, if T f11 ≤ the preset threshold T5 and T f22 ≤ the preset threshold T5, then no result is output; if T f33 ≤ the preset threshold T5, then it is determined that the cause of the vehicle undervoltage fault is other reasons that need to be manually checked.

[0009] Further, when the vehicle is not in the lower high-voltage state, based on the vehicle type and the power battery power, determining that the cause of the vehicle undervoltage fault is low power or DCDC not working properly includes: Judging the vehicle type, obtaining the power standard of this vehicle type based on the vehicle type, judging whether the power battery meets the standard. If it does not meet the standard, it is determined that the cause of the vehicle undervoltage fault is low power. If it meets the standard, it is determined that the cause of the vehicle undervoltage fault is that DCDC is not working properly.

[0010] Further, when a vehicle undervoltage fault occurs and the vehicle is in the ON gear, based on the DCDC working state, power battery parameters, vehicle type, and vehicle speed of the vehicle, determining the cause of the vehicle undervoltage fault includes: Judging whether the DCDC normal working conditions are met. If not, it is determined that the cause of the vehicle undervoltage fault is that the DCDC working conditions are not met; if met, then judge whether the power battery is normal; If the power battery is not normal, determine the cause of the vehicle undervoltage fault through the fault code output by the high-voltage system and the relevant parameters of the high-voltage system; if the power battery is normal, judge whether the DCDC output voltage is normal; If it is judged that the DCDC output voltage is not normal, determine the cause of the vehicle undervoltage fault by judging whether the DCDC output current is normal; if it is judged that the DCDC output voltage is normal, based on the vehicle type, power battery parameters, and vehicle speed, determine the cause of the vehicle undervoltage fault.

[0011] Further, the determining the cause of the vehicle undervoltage fault based on the vehicle type, power battery parameters, and vehicle speed includes: Judging the vehicle type, obtaining the power standard of this vehicle type based on the vehicle type, judging whether the power battery meets the standard. If it meets the standard, it is determined that the cause of the vehicle undervoltage fault is that DCDC is not working properly; When the vehicle type is range-extended or hybrid and the power battery power does not meet the standard, judge whether the charging condition is met. If the charging condition is not met, it is determined that the cause of the vehicle undervoltage fault is that the power battery does not meet the charging condition; if the charging condition is met, then judge whether the fuel quantity meets the standard. If the fuel quantity meets the standard, it is determined that the cause of the vehicle undervoltage fault is that the range extender is abnormal; if the fuel quantity does not meet the standard, judge whether the vehicle speed exceeds the preset vehicle speed. If it exceeds, it is determined that the cause of the vehicle undervoltage fault is dynamic power consumption with low fuel quantity and low power. If it does not exceed, it is determined that the cause of the vehicle undervoltage fault is static power consumption with low fuel quantity and low power; When the vehicle type is pure electric and the power battery power is not up to standard, it is judged whether the vehicle speed exceeds the preset vehicle speed. If it exceeds, it is determined that the cause of the vehicle undervoltage fault is dynamic power consumption due to low power. If it does not exceed, it is determined that the cause of the vehicle undervoltage fault is static power consumption due to low power.

[0012] A vehicle undervoltage fault cause analysis system in the present invention is used to implement the above vehicle undervoltage fault cause analysis method; the system includes: An undervoltage fault judgment module, which is used for collecting vehicle data and judging whether an undervoltage fault occurs; A first analysis module, which is used to determine the cause of the vehicle undervoltage fault based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state when a vehicle undervoltage fault occurs and the vehicle is in the OFF gear; A second analysis module, which is used to determine the cause of the vehicle undervoltage fault based on the DCDC working state of the vehicle, the power battery parameters, the vehicle type, and the vehicle speed when a vehicle undervoltage fault occurs and the vehicle is in the ON gear.

[0013] A vehicle in the present invention includes the above vehicle undervoltage fault cause analysis system.

[0014] The beneficial effects of the present invention are: (1) After a vehicle undervoltage fault occurs in the present invention, by screening different causes and obtaining the final cause of the vehicle undervoltage fault, it can improve the fault handling efficiency of the repair station, reduce the time consumption of engineers for analyzing the fault problem, reduce the after-sales cost and labor cost, and at the same time can provide a useful reference for optimizing the function scheme.

[0015] (2) The present invention automatically screens most of the causes that may lead to vehicle undervoltage faults, and does not require high professionalism or repair skills, enabling users or 4S store repair personnel to obtain the cause of the vehicle undervoltage fault in a timely manner. Only when the cause cannot be automatically screened out and the 4S store repair personnel cannot repair it, it is necessary to return to the factory for repair, improving the user experience. Description of the Drawings

[0016] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration: Figure 1 It is a schematic flow chart of the vehicle undervoltage fault cause analysis method of the present invention; Figure 2 It is a schematic flow chart of the vehicle undervoltage fault cause analysis method of the present invention when a vehicle undervoltage fault occurs and the vehicle is in the OFF gear; Figure 3 It is a schematic flow chart of the vehicle undervoltage fault cause analysis method of the present invention when a vehicle undervoltage fault occurs and the vehicle is in the ON gear. Specific implementation mode

[0017] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0018] As Figures 1 - 3 shown, a method for analyzing the causes of vehicle undervoltage faults in this embodiment includes: When a vehicle undervoltage fault occurs and the vehicle is in the OFF gear, based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle's high-voltage state, the power battery parameters, and the DCDC working state, determine the cause of the vehicle undervoltage fault; When a vehicle undervoltage fault occurs and the vehicle is in the ON gear, based on the DCDC working state of the vehicle, the power battery parameters, the vehicle type, and the vehicle speed, determine the cause of the vehicle undervoltage fault.

[0019] After determining the cause of the vehicle undervoltage fault, the result can be displayed and output through the vehicle-mounted screen, or the result can be sent to the cloud or the user's mobile terminal. By screening different causes after a vehicle undervoltage fault occurs and obtaining the final cause of the vehicle undervoltage fault, it is possible to improve the fault handling efficiency of the repair station, reduce the time consumption of engineers analyzing the fault problem, lower the after-sales cost and labor cost, and at the same time provide a useful reference for optimizing the function scheme.

[0020] Moreover, most of the possible causes of vehicle undervoltage faults are automatically screened, which does not require high professionalism or repair skills, enabling users or 4S store repair personnel to obtain the cause of the vehicle undervoltage fault in a timely manner. Only when the cause cannot be automatically screened out and the 4S store repair personnel cannot perform repairs is it necessary to return to the factory for repair, improving the user experience.

[0021] In this embodiment, based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle's high-voltage state, the power battery parameters, and the DCDC working state, determining the cause of the vehicle undervoltage fault includes: Judge whether there is power loss during the software flashing process. If it is judged to be yes, determine that the cause of the vehicle undervoltage fault is power loss during the software flashing process; if it is judged to be no, based on the wake-up reasons and durations of each controller, the vehicle's high-voltage state, the power battery parameters, and the DCDC working state, determine the cause of the vehicle undervoltage fault.

[0022] In this embodiment, the determining the cause of the vehicle undervoltage fault based on the wake-up reasons and durations of each controller, the vehicle's high-voltage state, the power battery parameters, and the DCDC working state includes: If the DCDC output voltage is U1 for a duration not less than T1, then obtain the time point T when the DCDC output voltage drops from U1 to U2 f1; where U1 refers to the DCDC output voltage under high voltage, and U2 refers to the DCDC output voltage under low voltage; If the duration of the vehicle in the ON gear is not less than the preset threshold T2, then obtain the time point T when the vehicle exits the ON gear f2 ; Obtain the time point T when the undervoltage fault occurs 欠压 , and calculate the time interval T between voltage change moments f11 =∣T 欠压 -T f1 ∣ and T f22 =∣T 欠压 -T f2 ∣; If T f11 is less than the preset threshold T3 or T f22 is less than the preset threshold T4, then determine that the cause of the vehicle undervoltage fault is battery performance attenuation or damage; If T f11 > the preset threshold T5 or T f22 > the preset threshold T5, then determine that the cause of the vehicle undervoltage fault is the vehicle has been parked for a long time; If T f11 ≤ the preset threshold T5 and T f22 ≤ the preset threshold T5, then no result is output.

[0023] In this embodiment, determining the cause of the vehicle undervoltage fault based on the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state further includes: Based on the wake-up reasons and durations of each controller, determine whether there is a controller with a wake-up reason exceeding the expected duration.

[0024] If there is a wake-up reason for the controller that exceeds the expected duration, determine the corresponding vehicle under-voltage fault reason based on the wake-up reason that exceeds the expected duration. For example: If the wake-up condition 1 of controller 0 exceeds the expected duration, determine that the vehicle under-voltage fault reason is battery thermal runaway. If the wake-up condition 2 of controller 0 exceeds the expected duration, determine that the vehicle under-voltage fault reason is abnormal battery cell temperature. If the wake-up condition 3 of controller 0 exceeds the expected duration, determine that the vehicle under-voltage fault reason is abnormal battery controller hardware. If the wake-up condition 1 of controller 1 exceeds the expected duration, determine that the vehicle under-voltage fault reason is signal jump of switch 1. If the wake-up condition 2 of controller 1 exceeds the expected duration, determine that the vehicle under-voltage fault reason is adhesion of switch 2. If the wake-up condition 3 of controller 1 exceeds the expected duration, determine that the vehicle under-voltage fault reason is abnormal remote control. If the wake-up condition 1 of controller N exceeds the expected duration, determine that the vehicle under-voltage fault reason is door state change. If the wake-up condition 2 of controller N exceeds the expected duration, determine that the vehicle under-voltage fault reason is abnormal double flash activation. If the wake-up condition 3 of controller N exceeds the expected duration, determine that the vehicle under-voltage fault reason is repeated key sensing. It should be noted that controller 0, controller 1, controller N, etc. are all for illustration purposes, and the numbers of the above controllers are only for distinction and there are no restrictions on the quantity, etc.

[0025] Moreover, after determining the corresponding vehicle under-voltage fault reason based on the wake-up reason that exceeds the expected duration, output the specific reason. The result can be displayed and output through the in-vehicle screen, or the result can be sent to the cloud or the user's mobile terminal.

[0026] If there is no controller with a wake-up reason that exceeds the expected duration, determine whether the vehicle has been de-energized; When the vehicle is not in the de-energized state, based on the vehicle type and the power battery power, determine that the vehicle under-voltage fault reason is low power or DCDC not working properly; When the vehicle is in the de-energized state, if the duration of the DCDC output voltage being U1 is less than T1, obtain the time point T when the DCDC output voltage drops from U1 to U2 f3 and obtain the time point T of the occurrence of the under-voltage fault 欠压 and calculate the voltage change time interval T f33 =∣T 欠压 -T f3 ∣. If T f33 > the preset threshold T5, determine that the vehicle under-voltage fault reason is the vehicle has been parked for a long time.

[0027] In this embodiment, if T f33 ≤ the preset threshold T5, determine that the vehicle under-voltage fault reason is other reasons that need to be manually checked.

[0028] In this embodiment, when the vehicle is not in the low-voltage state, based on the vehicle type and the power battery power, determining the cause of the vehicle under-voltage fault as low power or the DCDC not working properly includes: Judging the vehicle type, obtaining the power standard of this vehicle type based on the vehicle type, judging whether the power battery meets the standard. If it does not meet the standard, it is determined that the cause of the vehicle under-voltage fault is low power. If it meets the standard, it is determined that the cause of the vehicle under-voltage fault is that the DCDC is not working properly.

[0029] In this embodiment, when a vehicle under-voltage fault occurs and the vehicle is in the ON gear, based on the DCDC working state, power battery parameters, vehicle type, and vehicle speed of the vehicle, determining the cause of the vehicle under-voltage fault includes: Judging whether the DCDC normal working conditions are met. If not, it is determined that the cause of the vehicle under-voltage fault is that the DCDC working conditions are not met. If met, then judge whether the power battery is normal; If the power battery is not normal, determine the cause of the vehicle under-voltage fault through the fault code output by the high-voltage system and the relevant parameters of the high-voltage system. For example: If the fault code output by the high-voltage system is fault code 1, it is determined that the cause of the vehicle under-voltage fault is thermal runaway of the power battery. If the fault codes output by the high-voltage system are fault codes 2 and 3 and the cell voltage of the high-voltage system is abnormal, it is determined that the cause of the vehicle under-voltage fault is abnormal power battery cells. If the fault code output by the high-voltage system is fault code 4 and the insulation resistance of the high-voltage system is abnormal, it is determined that the cause of the vehicle under-voltage fault is power battery insulation fault. If the fault code output by the high-voltage system is other fault codes and one or more of the remaining parameters such as current, voltage, insulation resistance, and temperature of the high-voltage system are abnormal, it is determined that the cause of the vehicle under-voltage fault is other high-voltage system faults.

[0030] If the power battery is normal, judge whether the DCDC output voltage is normal. At this time, if it is judged that the DCDC output voltage is not normal, determine the cause of the vehicle under-voltage fault by judging whether the DCDC output current is normal. At this time, if the DCDC output current is normal, it is determined that the cause of the vehicle under-voltage fault is an abnormal power supply circuit of the fuse box. If the DCDC output current is not normal, it is determined that the cause of the vehicle under-voltage fault is an abnormal DCDC output circuit.

[0031] If it is judged that the DCDC output voltage is normal, determine the cause of the vehicle under-voltage fault based on the vehicle type, power battery parameters, and vehicle speed.

[0032] In this embodiment, determining the cause of the vehicle under-voltage fault based on the vehicle type, power battery parameters, and vehicle speed includes: Judging the vehicle type, obtaining the power standard of this vehicle type based on the vehicle type, judging whether the power battery meets the standard. If it meets the standard, it is determined that the cause of the vehicle under-voltage fault is that the DCDC is not working properly; When the vehicle type is range-extended or hybrid and the power battery charge is not up to standard, it is judged whether the charging condition is met. If the charging condition is not met, it is determined that the reason for the vehicle undervoltage fault is that the power battery does not meet the charging condition; if the charging condition is met, it is judged whether the fuel quantity is up to standard. If the fuel quantity is up to standard, it is determined that the reason for the vehicle undervoltage fault is the abnormal range extender; if the fuel quantity is not up to standard, it is judged whether the vehicle speed exceeds the preset vehicle speed. If it exceeds, it is determined that the reason for the vehicle undervoltage fault is the dynamic power consumption with low fuel quantity and low battery charge. If it does not exceed, it is determined that the reason for the vehicle undervoltage fault is the static power consumption with low fuel quantity and low battery charge; When the vehicle type is pure electric and the power battery charge is not up to standard, it is judged whether the vehicle speed exceeds the preset vehicle speed. If it exceeds, it is determined that the reason for the vehicle undervoltage fault is the dynamic power consumption with low battery charge. If it does not exceed, it is determined that the reason for the vehicle undervoltage fault is the static power consumption with low battery charge.

[0033] A vehicle undervoltage fault cause analysis system in this embodiment is used to implement the above vehicle undervoltage fault cause analysis method; the system includes: An undervoltage fault judgment module, which is used to collect vehicle data and judge whether an undervoltage fault occurs; A first analysis module, which is used to determine the reason for the vehicle undervoltage fault based on the software flashing situation of the vehicle, the wake-up reasons and durations of each controller, the vehicle high-voltage state, the power battery parameters, and the DCDC working state when a vehicle undervoltage fault occurs and the vehicle is in the OFF gear; A second analysis module, which is used to determine the reason for the vehicle undervoltage fault based on the DCDC working state of the vehicle, the power battery parameters, the vehicle type, and the vehicle speed when a vehicle undervoltage fault occurs and the vehicle is in the ON gear.

[0034] A vehicle in this embodiment includes the above vehicle undervoltage fault cause analysis system.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for analyzing the cause of vehicle undervoltage fault, characterized in that: include: When a vehicle undervoltage fault occurs and the vehicle is in the OFF gear, the cause of the vehicle undervoltage fault is determined based on the vehicle's software flashing status, the wake-up reasons and duration of each controller, the vehicle's high voltage status, the power battery parameters, and the DCDC working status; When a vehicle undervoltage fault occurs and the vehicle is in the ON gear, the cause of the vehicle undervoltage fault is determined based on the vehicle's DCDC working status, power battery parameters, vehicle type and vehicle speed.

2. The vehicle undervoltage fault cause analysis method according to claim 1, characterized in that: Based on the vehicle's software flashing status, the wake-up reasons and duration of each controller, the vehicle's high voltage status, power battery parameters, and DCDC working status, determine the cause of the vehicle's undervoltage fault, including: Determine whether the battery is low during the software flashing process. If so, determine that the cause of the vehicle's undervoltage fault is the battery low during the software flashing process. If not, determine the cause of the vehicle's undervoltage fault based on the wake-up reasons and duration of each controller, the high-voltage status of the vehicle, the power battery parameters, and the DCDC working status.

3. The vehicle undervoltage fault cause analysis method according to claim 2, characterized in that: The determination of the cause of the vehicle undervoltage fault based on the wake-up reasons and duration of each controller, the high voltage state of the vehicle, the power battery parameters and the DCDC working state includes: If the DCDC output voltage is U1 for a duration not less than T1, the time point when the DCDC output voltage drops from U1 to U2 is T f1 ; Among them, U1 refers to the DCDC output voltage when the upper high voltage is on, and U2 refers to the DCDC output voltage when the lower high voltage is on; If the vehicle is in the ON position for a duration not less than the preset threshold value T2, the time point when the vehicle exits the ON position is obtained as T f2 ; Get the time point T when the undervoltage fault occurs 欠压 , and calculate the voltage change time interval T f11 =|T 欠压 -T f1 ∣ and T f22 =|T 欠压 -T f2 ∣; If T f11 Less than the preset threshold T3 or T f22 If the value is less than the preset threshold value T4, it is determined that the cause of the vehicle undervoltage fault is battery performance degradation or damage; If T f11 >Preset threshold T5 or T f22 > preset threshold value T5, it is determined that the cause of the vehicle undervoltage fault is that the vehicle has been parked for a long time.

4. The vehicle undervoltage fault cause analysis method according to claim 3 is characterized in that: The method of determining the cause of the vehicle undervoltage fault based on the wake-up reasons and durations of each controller, the high voltage state of the vehicle, the power battery parameters and the DCDC working state, further includes: Based on the wake-up reasons and duration of each controller, determine whether there is a controller wake-up reason that exceeds the expected duration. If yes, determine the corresponding vehicle undervoltage fault cause based on the wake-up reason that exceeds the expected duration; if no, determine whether the vehicle is under high voltage; When the vehicle is not in the low-voltage state, based on the vehicle type and the power battery level, it is determined that the cause of the vehicle undervoltage fault is low power or the DCDC is working normally; When the vehicle is in the low-voltage state, if the DCDC output voltage is U1 for a duration less than T1, the time point when the DCDC output voltage drops from U1 to U2 is T f3 , and obtain the time point T when the undervoltage fault occurs 欠压 , and calculate the voltage change time interval T f33 =|T 欠压 -T f3 ∣, if T f33 > preset threshold value T5, it is determined that the cause of the vehicle undervoltage fault is that the vehicle has been parked for a long time.

5. The vehicle undervoltage fault cause analysis method according to claim 4 is characterized in that: If T f11 ≤ preset threshold T5 and T f22 ≤ preset threshold T5, no result is output; if T f33 ≤ the preset threshold T5, it is determined that the cause of the vehicle undervoltage fault is other reasons that require manual investigation.

6. The vehicle undervoltage fault cause analysis method according to claim 4, characterized in that: When the vehicle is not in the low-voltage state, based on the vehicle type and the power battery level, determining that the cause of the vehicle undervoltage fault is low power or that the DCDC is working normally includes: Determine the vehicle type, obtain the power standard of the vehicle model based on the vehicle type, and determine whether the power battery meets the standard. If it does not meet the standard, determine that the cause of the vehicle undervoltage fault is low power. If it meets the standard, determine that the cause of the vehicle undervoltage fault is that the DCDC is not working properly.

7. The vehicle undervoltage fault cause analysis method according to claim 1, characterized in that: When a vehicle undervoltage fault occurs and the vehicle is in the ON gear, determining the cause of the vehicle undervoltage fault based on the vehicle's DCDC working state, power battery parameters, vehicle type and vehicle speed includes: Determine whether the normal working conditions of DCDC are met. If not, determine that the cause of the vehicle undervoltage fault is that the DCDC working conditions are not met; if so, determine whether the power battery is normal; If the power battery is abnormal, the cause of the vehicle undervoltage fault is determined through the fault code output by the high-voltage system and the related parameters of the high-voltage system; if the power battery is normal, determine whether the DCDC output voltage is normal; If the DCDC output voltage is judged to be abnormal, the cause of the vehicle undervoltage fault is determined by judging whether the DCDC output current is normal; if the DCDC output voltage is judged to be normal, the cause of the vehicle undervoltage fault is determined based on the vehicle type, power battery parameters and vehicle speed.

8. The vehicle undervoltage fault cause analysis method according to claim 7, characterized in that: The determining of the cause of the vehicle undervoltage fault based on the vehicle type, power battery parameters and vehicle speed includes: Determine the vehicle type, obtain the power standard of the vehicle model based on the vehicle type, and determine whether the power battery meets the standard. If it does, determine that the cause of the vehicle undervoltage fault is that the DCDC is not working properly; When the vehicle type is an extended-range or hybrid vehicle, and the power battery power level does not meet the standard, determine whether the charging conditions are met. If the charging conditions are not met, determine that the cause of the vehicle undervoltage fault is that the power battery does not meet the charging conditions; if the charging conditions are met, determine whether the fuel level meets the standard. If the fuel level meets the standard, determine that the cause of the vehicle undervoltage fault is an abnormality in the range extender; if the fuel level does not meet the standard, determine whether the vehicle speed exceeds the preset speed. If it exceeds, determine that the cause of the vehicle undervoltage fault is low fuel and low power dynamic power consumption; if it does not exceed, determine that the cause of the vehicle undervoltage fault is low fuel and low power static power consumption; When the vehicle type is pure electric and the power battery power does not meet the standard, determine whether the vehicle speed exceeds the preset speed. If it exceeds, it is determined that the cause of the vehicle undervoltage fault is low power dynamic consumption. If it does not exceed, it is determined that the cause of the vehicle undervoltage fault is low power static consumption.

9. A vehicle undervoltage fault cause analysis system, characterized in that: Used to implement the vehicle undervoltage fault cause analysis method according to any one of claims 1 to 8; the system comprises: An undervoltage fault judgment module is used to collect vehicle data and judge whether an undervoltage fault occurs; The first analysis module is used to determine the cause of the vehicle undervoltage fault based on the vehicle software flashing status, the wake-up reasons and duration of each controller, the high voltage state of the whole vehicle, the power battery parameters and the DCDC working state when the vehicle undervoltage fault occurs and the vehicle is in the OFF gear; The second analysis module is used to determine the cause of the vehicle undervoltage fault based on the vehicle's DCDC working status, power battery parameters, vehicle type and vehicle speed when the vehicle undervoltage fault occurs and the vehicle is in the ON gear.

10. A vehicle, characterized in that: It includes the vehicle undervoltage fault cause analysis system as described in claim 9.

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