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CN-122026556-A - Electric vehicle and method for predicting state of charge of auxiliary battery of electric vehicle

CN122026556ACN 122026556 ACN122026556 ACN 122026556ACN-122026556-A

Abstract

The present invention relates to an electric vehicle and a method for predicting a state of charge of an auxiliary battery of the electric vehicle. An electric vehicle includes a main battery, an auxiliary battery, an electrical load, an electrical power converter, a switch, a memory, and a controller. The controller controls the on or off of the switch. When the switch is turned on, the low-voltage power converted by the power converter is supplied to the auxiliary battery for charging, and when the switch is turned off, the auxiliary battery is discharged. The controller acquires an output current value of the power converter after the vehicle is turned off and while the auxiliary battery is charged. The controller determines the state of charge of the auxiliary battery based on the obtained output current value of the power converter according to the correspondence relationship between the output current value of the power converter and the state of charge of the auxiliary battery after the vehicle is turned off and when the auxiliary battery is charged, which is stored in the memory, so that the state of charge of the auxiliary battery after the vehicle is turned off can be predicted even if the intelligent battery sensor is not provided in the vehicle.

Inventors

  • LI XIUKUN
  • LIN JINZHAO
  • Ren liuyi

Assignees

  • 现代自动车株式会社
  • 起亚株式会社

Dates

Publication Date
20260512
Application Date
20241107

Claims (20)

  1. 1. An electric vehicle, comprising: A main battery, an auxiliary battery, and an electrical load; a power converter electrically connected between the main battery and the auxiliary battery and configured to convert high-voltage power output from the main battery into low-voltage power; A switch electrically connected between the power converter and the auxiliary battery and configured such that when the switch is turned on, the low-voltage power converted by the power converter is supplied to the auxiliary battery and the operating power load, thereby charging the auxiliary battery, and when the switch is turned off, the auxiliary battery is discharged to supply power to the operating power load; A memory configured to store a consumption current value of an electric load operated after a vehicle is turned off and a correspondence relationship between an output current value of the electric power converter after the vehicle is turned off and when the auxiliary battery is charged and a state of charge of the auxiliary battery, and A controller configured to: after the vehicle is flameout, the switch is controlled to be turned on or off so as to control the auxiliary battery to charge; Acquiring an output current value of the power converter after the vehicle is flameout and when the auxiliary battery is charged; and determining the state of charge of the auxiliary battery after the vehicle is flameout based on the acquired output current value of the power converter according to the corresponding relation stored in the memory.
  2. 2. The electric vehicle of claim 1, wherein the controller is configured to: the switch is kept on after the vehicle is started, thereby assisting the continuous charging of the battery.
  3. 3. The electric vehicle according to claim 2, wherein the controller is configured to control the switch to be turned on according to an elapsed time and to control the switch to be turned off according to a calculated charge current value of the auxiliary battery or a predicted state of charge of the auxiliary battery; The charging current value of the auxiliary battery is equal to the difference value between the output current value of the power converter obtained in real time after the vehicle is flameout and when the auxiliary battery is charged and the consumption current value of the power load running after the vehicle is flameout and stored in the memory.
  4. 4. The electric vehicle of claim 3, wherein the controller is configured to: The control switch is turned on after a first reference period of time passes after the vehicle is turned off, and is turned off when the predicted state of charge of the auxiliary battery is greater than or equal to a reference charge threshold or the calculated charging current value of the auxiliary battery is less than the reference current threshold; the control switch is turned on every second reference period after the control switch is turned off, and the control switch is turned off when the predicted state of charge of the auxiliary battery is greater than or equal to the reference charge threshold value or the calculated charge current value of the auxiliary battery is less than the reference current threshold value.
  5. 5. The electric vehicle as set forth in claim 1, wherein the consumption current value of the electric load operated after the vehicle is turned off stored in the memory is calculated by the following equation: Wherein I A is a consumption current value of an electric load operated after the vehicle is turned off, which is stored in the memory, Is the output current value of the power converter in the ith test, Is the charging current value of the auxiliary battery in the ith test, and n is the number of tests in which the vehicle is turned off and the low-voltage power converted by the power converter is supplied to the auxiliary battery and the operating electric load.
  6. 6. The electric vehicle according to claim 1, wherein the correspondence is a map corresponding to a first map indicating a map between an output current value of the power converter at a specific charging time point of the auxiliary battery and a state of charge of the auxiliary battery and an ambient temperature after the vehicle is turned off and when the auxiliary battery is charged; The electric vehicle further includes an ambient temperature sensor configured to detect an ambient temperature outside the vehicle at a specific charging time point of each charging of the auxiliary battery; The controller is configured to determine a state of charge of the auxiliary battery on the map based on an ambient temperature detected by the ambient temperature sensor at a specific charging time point of each charging of the auxiliary battery and an output current value of the power converter acquired at the specific charging time point of each charging of the auxiliary battery when the auxiliary battery is charged after the vehicle is turned off.
  7. 7. The electric vehicle according to claim 6, wherein the output current value of the power converter at a specific charging time point of the auxiliary battery after the vehicle is turned off and when the auxiliary battery is charged in the first map is obtained by adding the same state of charge of the auxiliary battery in the second map, the charging current value of the auxiliary battery at the specific charging time point at the same ambient temperature, and the consumption current value of the electric load that is operated after the vehicle is turned off and stored in the memory; Wherein the second map indicates a mapping relationship between a charging current value of the auxiliary battery at a specific charging time point and a state of charge of the auxiliary battery and an ambient temperature.
  8. 8. The electric vehicle according to claim 7, wherein in the second map, the state of charge of the auxiliary battery ranges from 40% to 90%, the ambient temperature ranges from-20 ℃ to 25 ℃, and the specific charging time ranges from 5min to 30 min.
  9. 9. The electric vehicle of claim 1, wherein the controller is configured to: setting the dark current amount to zero after the vehicle is turned off; the difference in the state of charge of the auxiliary battery for the adjacent two predictions is calculated by the following equation: D=SOC m-1 -SOC m Wherein D is the difference, SOC m is the state of charge of the auxiliary battery predicted the previous time, SOC m is the state of charge of the auxiliary battery predicted currently, and m is an integer greater than or equal to 2; Determining whether the difference is greater than or equal to a reference value, increasing the amount of dark current by 1 when the difference is determined to be greater than or equal to the reference value, and keeping the amount of dark current unchanged when the difference is determined to be less than the reference value; and determining that the dark current problem occurs when the accumulated dark current quantity is greater than or equal to the reference dark current quantity threshold value.
  10. 10. The electric vehicle of claim 9, wherein the controller is configured to generate and transmit a diagnostic trouble code after determining that a dark current problem has occurred.
  11. 11. A method for predicting a state of charge of an auxiliary battery of an electric vehicle, the electric vehicle including a main battery, an auxiliary battery, a power converter electrically connected between the main battery and the auxiliary battery, a switch electrically connected between the power converter and the auxiliary battery, a memory, and a controller, the method comprising the steps of: After the vehicle is flameout, the controller controls the switch to be turned on or off so as to control the auxiliary battery to charge; Storing, by a memory, a consumption current value of an electric load operated after a vehicle is turned off and a correspondence between an output current value of an electric power converter after the vehicle is turned off and when an auxiliary battery is charged and an electric quantity state of the auxiliary battery; acquiring, by the controller, an output current value of the power converter after the vehicle is turned off and while the auxiliary battery is charged, and And the controller determines the state of charge of the auxiliary battery after the vehicle is flameout based on the acquired output current value of the power converter according to the corresponding relation stored in the memory.
  12. 12. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as recited in claim 11, further comprising the step of: after the vehicle is started, the switch is kept on by the controller, so that the auxiliary battery is continuously charged.
  13. 13. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as recited in claim 12, wherein the step of controlling the switch to be turned on or off by the controller after the vehicle is turned off comprises: Controlling the switch to be turned on according to the elapsed time, and controlling the switch to be turned off according to the calculated charge current value of the auxiliary battery or the predicted state of charge of the auxiliary battery; The charging current value of the auxiliary battery is equal to the difference value between the output current value of the power converter obtained in real time after the vehicle is flameout and when the auxiliary battery is charged and the consumption current value of the power load running after the vehicle is flameout and stored in the memory.
  14. 14. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as recited in claim 13, wherein the step of controlling the switch to be turned on or off by the controller after the vehicle is turned off further comprises: The switch is controlled to be turned on by the controller after a first reference period of time elapses after the vehicle is turned off, and is controlled to be turned off by the controller when the predicted state of charge of the auxiliary battery is greater than or equal to the reference charge threshold value or the calculated charge current value of the auxiliary battery is less than the reference current threshold value, and The controller controls the switch to be turned on every second reference period after the controller controls the switch to be turned off, and controls the switch to be turned off when the predicted state of charge of the auxiliary battery is greater than or equal to the reference charge threshold value or the calculated charge current value of the auxiliary battery is less than the reference current threshold value.
  15. 15. The method for predicting the state of charge of an auxiliary battery of an electric vehicle of claim 11, wherein the consumption current value of the electric load operated after the vehicle is turned off stored in the memory is calculated by the following equation: Wherein I A is a consumption current value of an electric load operated after the vehicle is turned off, which is stored in the memory, Is the output current value of the power converter in the ith test, Is the charging current value of the auxiliary battery in the ith test, and n is the number of tests in which the vehicle is turned off and the low-voltage power converted by the power converter is supplied to the auxiliary battery and the operating electric load.
  16. 16. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as set forth in claim 11, wherein the correspondence is a map corresponding to a first map indicating a map between an output current value of the power converter at a specific charging time point of the auxiliary battery after the vehicle is turned off and when the auxiliary battery is charged and the state of charge of the auxiliary battery and an ambient temperature, the electric vehicle further including an ambient temperature sensor, the method further comprising the step of: Detecting an ambient temperature outside the vehicle by an ambient temperature sensor at a specific charging time point of each charging of the auxiliary battery, and And determining the state of charge of the auxiliary battery on the mapping curve according to the ambient temperature detected by the ambient temperature sensor at the specific charging time point of each charging of the auxiliary battery and the output current value of the power converter acquired at the specific charging time point of each charging of the auxiliary battery when the auxiliary battery is charged after the vehicle is flameout.
  17. 17. The method for predicting the state of charge of an auxiliary battery of an electric vehicle according to claim 16, wherein the output current value of the power converter at a specific charging time point of the auxiliary battery after the vehicle is turned off and when the auxiliary battery is charged in the first map is obtained by adding the same state of charge of the auxiliary battery in the second map, the charging current value of the auxiliary battery at the specific charging time point at the same ambient temperature, and the consumption current value of the electric load operated after the vehicle is turned off stored in the memory; Wherein the second map indicates a mapping relationship between a charging current value of the auxiliary battery at a specific charging time point and a state of charge of the auxiliary battery and an ambient temperature.
  18. 18. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as set forth in claim 17, wherein in the second map, the state of charge of the auxiliary battery ranges from 40% to 90%, the ambient temperature ranges from-20 ℃ to 25 ℃, and the specific charging time ranges from 5min to 30 min.
  19. 19. The method for predicting the state of charge of an auxiliary battery of an electric vehicle as recited in claim 11, further comprising the step of: setting, by the controller, the amount of dark current to zero after the vehicle is turned off; Calculating, by the controller, a difference in the state of charge of the auxiliary battery of the adjacent two predictions by the following equation: D=SOC m-1 -SOC m Wherein D is the difference, SOC m is the state of charge of the auxiliary battery predicted the previous time, SOC m is the state of charge of the auxiliary battery predicted currently, and m is an integer greater than or equal to 2; Determining, by the controller, whether the difference is greater than or equal to a reference value, increasing, by the controller, the amount of dark current by 1 when the difference is determined to be greater than or equal to the reference value, and leaving, by the controller, the amount of dark current unchanged when the difference is determined to be less than the reference value, and When the accumulated dark current amount is greater than or equal to the reference dark current amount threshold, the controller determines that a dark current problem occurs.
  20. 20. The method for predicting the state of charge of an auxiliary battery of an electric vehicle of claim 19, further comprising the step of generating and transmitting a diagnostic trouble code by the controller after the controller determines that the dark current problem is occurring.

Description

Electric vehicle and method for predicting state of charge of auxiliary battery of electric vehicle Technical Field The present invention relates to an electric vehicle and a method for predicting a state of charge of an auxiliary battery of the electric vehicle. Background Existing electric vehicles (ELECTRIC VEHICLE, EV) utilize smart battery sensors (INTELLIGENT BATTERY SENSOR, IBS) fitted in EVs to monitor the status of the 12V auxiliary battery in real time. The IBS transmits the monitored State of Charge (SOC), functional State (State of Function, SOF), health (SOH), etc. of the auxiliary battery to the vehicle control unit (Vehicle Control Unit, VCU) through the in-vehicle local interconnect network (Local Interconnect Network, LIN). The VCU determines whether to charge the auxiliary battery according to the SOC of the auxiliary battery. For example, when the SOC of the auxiliary battery is less than or equal to 80%, the VCU may determine that the auxiliary battery needs to be charged. At this time, the Low voltage direct current-direct current converter (Low-voltage Direct Current-Direct Current Converter, LDC) may convert high voltage power of a high voltage battery (e.g., a main battery) of the vehicle into Low voltage power and supply the converted Low voltage power to the auxiliary battery. In an internal combustion engine (Internal Combustion Engine, ICE) vehicle, IBS plays a great role because it can improve cold start (cold cranking) efficiency and fuel efficiency. In comparison with ICE vehicles, EVs have no mechanical structure such as an engine generator, and no Idle Stop & Go (ISG) function, without considering the influence of cold start efficiency and fuel efficiency. Furthermore, even if the auxiliary battery is located in the engine compartment, the ambient temperature cannot exceed 80 ℃, so the health of the battery is not affected by the ambient conditions. Thus, for EVs, the importance of the predicted battery temperature state (Battery Temperature Model, BTM) of IBS and the function of SOF is reduced. Therefore, in summary, in the EV vehicle, IBS is required only when the auxiliary battery is charged. Since IBS only works when charging the auxiliary battery in the EV and equipping the IBS increases the cost of the EV, it is necessary to provide an EV and a method for the EV so that the SOC of the auxiliary battery can be predicted without equipping the IBS so as not to affect the charging of the auxiliary battery. The above description of the background is only for the purpose of facilitating a thorough understanding of the present invention's aspects (in terms of the means of technology used, the technical problems solved, and the technical effects produced, etc.) and should not be taken as an acknowledgement or any form of suggestion that this message constitutes prior art that is already known to a person skilled in the art. Disclosure of Invention An object of the present invention is to provide an electric vehicle and a method for predicting a State of Charge (SOC) of an auxiliary battery of the electric vehicle, in which the SOC of the auxiliary battery can be predicted without a smart battery sensor (INTELLIGENT BATTERY SENSOR, IBS). According to an embodiment of the present invention, there is provided an electric vehicle including a main battery, an auxiliary battery, and an electric load, a power converter electrically connected between the main battery and the auxiliary battery and configured to convert high-voltage electric power output from the main battery into low-voltage electric power, a switch electrically connected between the power converter and the auxiliary battery and configured to supply the low-voltage electric power converted by the power converter to the auxiliary battery and the operating electric load when the switch is on, thereby charging the auxiliary battery, and to discharge the auxiliary battery to supply electric power to the operating electric load when the switch is off, a memory configured to store a consumed electric current value of the operating electric load after the vehicle is turned off, and a correspondence between an output electric current value of the power converter after the vehicle is turned off and at the time of charging the auxiliary battery and an SOC of the auxiliary battery, and a controller configured to control on or off of the switch after the vehicle to control charging of the auxiliary battery, acquire an output electric current value of the power converter after the vehicle is turned off and at the time of charging the auxiliary battery, and determine a post-off electric current value of the auxiliary battery based on the acquired electric current value of the auxiliary battery stored in the memory. The controller may be configured to maintain the switch on after the vehicle is started, thereby assisting in continuous charging of the battery. The controller may be configured to control the switch to be turned on acco