METHOD FOR CONTROLLING CHARGING VOLTAGE OF 12V AUXILIARY BATTERY FOR HYBRID VEHICLE

• US 20110133694A1
• Filed: 11/08/2010
• Published: 06/09/2011
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Inventors: Song, Hong Seok
• Granted Patent: US 8,928,272 B2
• Time in Patent Office: Days
• US Class Current: 320/109
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 1/02 to electric heating circuits
• CPC Class Codes: B60L 1/14 to electric lighting circuits
• CPC Class Codes: B60L 15/007 Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 53/11 DC charging controlled by the charging station, e.g. mode 4
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

The present invention provides a method for controlling a charging voltage of a 12V auxiliary battery for a hybrid vehicle, which can (1) improve charging efficiency of an auxiliary battery by increasing the output voltage of a DC-DC converter during cold start when the outside air temperature is low, (2) improve the charging efficiency of the auxiliary battery by increasing or decreasing the output power of the DC-DC converter according to the state of charge of the auxiliary battery and by increasing the output voltage of the DC-DC converter when many electrical loads are turned on, and (3) allow the DC-DC converter to provide continuous power supply for charging the auxiliary battery by turning on a main switch disposed between a high voltage battery and the DC-DC converter based on a reverse power conversion operation of the DC-DC converter even in the case where the voltage of the auxiliary battery falls below 9V.

Claims

1. A method for controlling a charging voltage of a 12V auxiliary battery for a hybrid vehicle, the method comprising:

comparing the outside air temperature with a boundary temperature after the vehicle is started;

if the outside air temperature is lower than the boundary temperature, measuring the voltage of a 12V auxiliary battery; and

if the voltage of the 12V auxiliary battery is beyond a predetermined reference voltage range, increasing the output voltage at a DC-DC converter.

2. The method of claim 1, wherein if the voltage of the 12V auxiliary battery is lower than the predetermined reference voltage, the DC-DC converter operates in a rapid charge mode in which the output voltage is significantly increased.

3. The method of claim 1, wherein if the voltage of the 12V auxiliary battery is higher than the predetermined reference voltage, the DC-DC converter operates in a trickle charge mode in which the output voltage is slightly increased.

4. The method of claim 1, wherein if the outside air temperature is higher than the boundary temperature, the DC-DC converter operates in a normal mode.

5. The method of claim 1, further comprising:

measuring the current charged into or discharged from the 12V auxiliary battery;

if the accumulated absolute value of the charge or discharge current is higher than a boundary value, controlling the DC-DC converter to operate in a normal mode; and

if the accumulated absolute value of the charge or discharge current is lower than the boundary value, controlling the DC-DC converter to operate in a mode in which its output voltage is significantly or slightly increased.

6. A method for controlling a charging voltage of a 12V auxiliary battery for a hybrid vehicle, the method comprising:

comparing the current amount of 12V electrical loads with a reference load value after the vehicle is started;

if the amount of 12V electrical loads is smaller than the reference load value, increasing the output voltage of a DC-DC converter to perform a mode for improving charging efficiency of a 12V auxiliary battery;

if the amount of 12V electrical loads is greater than the reference load value, determining the state of charge of the 12V auxiliary battery; and

if the state of charge of the 12V auxiliary battery is lower than a charge boundary value, entering a mode for enhancing the charging speed of the 12V auxiliary battery.

7. The method of claim 6, further comprising if the state of charge of the 12V auxiliary battery is higher than a charge boundary value, entering a mode for improving fuel efficiency in which the output voltage of the DC-DC converter is saved by decreasing the output voltage of the DC-DC converter.

8. A method for controlling a charging voltage of a 12V auxiliary battery for a hybrid vehicle, the method comprising:

comparing the voltage of a 12V auxiliary battery with a low limit value for operation of a main switch, wherein the main switch connects a high voltage battery to a DC-DC converter, and a variety of controllers after the vehicle is started;

if the voltage of the 12V auxiliary battery falls below the low limit value, allowing the DC-DC converter to perform a reverse power conversion;

allowing electrical energy to be transferred from the 12V auxiliary battery to a high voltage capacitor and stored in the high voltage capacitor;

allowing the DC-DC converter to perform a forward power conversion for a predetermined short period of time; and

allowing high voltage energy of the high voltage capacitor to be supplied to the 12V auxiliary battery through the DC-DC converter.

9. The method of claim 8, further comprising:

allowing a voltage of more than a low limit voltage to be applied from the 12V auxiliary battery to the main switch and the controllers to turn on the main switch; and

allowing the DC-DC converter to be normally driven by the power of the high voltage battery due to the turning on of the main switch.