Method and apparatus for electric power management in a vehicle

• US 8,742,615 B2
• Filed: 01/14/2011
• Issued: 06/03/2014
• Est. Priority Date: 01/14/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Gopalakrishnan, Suresh, Namuduri, Chandra S., Hoinka, Mark C., Naik, Sanjeev M., Hao, Lei
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US13/006,542
• Publication Number:
  US 20120181854A1
• Time in Patent Office: 1,236 Days
• Field of Search: 307/9, 307/1, 307/10.1, 701/22
• US Class Current: 307/9.1
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

An on-vehicle DC/DC converter transforms high-voltage electric power originating from an on-vehicle high-voltage source to low-voltage electric power at a regulated voltage level. The low-voltage electric power is distributed by a low-voltage bus. A method for operating the DC/DC converter includes monitoring a state of charge and a temperature of a low-voltage battery connected to the low-voltage bus, setting a DC/DC converter command to a nominal voltage level as a function of the state of charge and temperature of the low-voltage battery, monitoring a total low-voltage electric load, and adjusting the DC/DC converter command to a minimum low-voltage reference voltage when the vehicle is operating below a predetermined speed and the total low-voltage electric load is greater than a predetermined load.

Claims

1. Method for operating an on-vehicle DC/DC converter configured to transform high-voltage electric power originating from an on-vehicle high-voltage source to low-voltage electric power at a regulated voltage level, the low-voltage electric power distributed by a low-voltage bus, the method comprising:

monitoring a state of charge and a temperature of a low-voltage battery connected to the low-voltage bus;

setting a DC/DC converter command to a nominal voltage level as a function of the state of charge and temperature of the low-voltage battery;

monitoring a total low-voltage electric load; and

adjusting the DC/DC converter command to a minimum low-voltage reference voltage when the vehicle is operating below a predetermined speed and the total low-voltage electric load is greater than a predetermined load.

2. The method of claim 1, wherein adjusting the DC/DC converter command comprises adjusting the DC/DC converter command to the minimum low-voltage reference voltage is effected only when the total low-voltage electric load comprises a vehicle headlamp.

3. The method of claim 2, further comprising selectively disabling at least one low-voltage electric load when the total low-voltage electric load is greater than the predetermined load.

4. The method of claim 1, further comprising:

monitoring a voltage across the low-voltage bus; and

activating at least one low-voltage electric load when the monitored voltage across the low-voltage bus exceeds a predetermined first voltage.

5. The method of claim 4, further comprising deactivating the DC/DC converter subsequent to activating said at least one low-voltage electric load when the voltage across the low-voltage bus exceeds a predetermined second voltage greater than the predetermined first voltage.

6. The method of claim 5, further comprising reactivating the DC/DC converter subsequent to deactivating the DC/DC converter when the voltage level across the low-voltage bus is less than a predetermined third voltage less than the predetermined second voltage.

7. Method for operating an on-vehicle DC/DC converter configured to transform high-voltage electric power originating from an on-vehicle high-voltage source to low-voltage electric power at a regulated voltage level, the low-voltage electric power distributed by a low-voltage bus, the method comprising:

monitoring a state of charge and a temperature of a low-voltage battery connected to the low-voltage bus;

setting a DC/DC converter command to a nominal voltage level as a function of the state of charge and temperature of the low-voltage battery;

monitoring a low-voltage electric load comprising a vehicle headlamp; and

adjusting the DC/DC converter command to a minimum low-voltage reference voltage when the vehicle is operating below a predetermined speed and the total low-voltage electric load is greater than a predetermined load;

monitoring a voltage across the low-voltage bus; and

activating at least one low-voltage electric load when the monitored voltage across the low-voltage bus exceeds a predetermined first voltage.

8. The method of claim 7, further comprising deactivating the DC/DC converter subsequent to activating said at least one low-voltage electric load when the voltage across the low-voltage bus exceeds a predetermined second voltage greater than the predetermined first voltage.

9. The method of claim 8, further comprising reactivating the DC/DC converter subsequent to deactivating the DC/DC converter when the voltage level across the low-voltage bus is less than a predetermined third voltage less than the predetermined second voltage.

10. The method of claim 7, wherein activation of said at least one low-voltage electric load is for a predetermined duration.

11. Method for operating an on-vehicle DC/DC converter configured to transform high-voltage electric power originating from an on-vehicle high-voltage source to low-voltage electric power at a regulated voltage level, the low-voltage electric power distributed by a low-voltage bus, the method comprising:

monitoring a state of charge and a temperature of a low-voltage battery connected to the low-voltage bus;

setting a DC/DC converter command to a nominal voltage level as a function of the state of charge and temperature of the low-voltage battery;

monitoring a total low-voltage electric load including a passive low-voltage electric load, an active low-voltage load, a controllable low-voltage electric load, and a charge load for the low-voltage battery;

monitoring a voltage across the low-voltage bus; and

activating the controllable low-voltage electric load when the monitored voltage across the low-voltage bus exceeds a first voltage.

12. The method of claim 11, further comprising deactivating the DC/DC converter when the voltage across the low-voltage bus exceeds a predetermined second voltage subsequent to activating the controllable low-voltage electric load.

13. The method of claim 12, further comprising reactivating the DC/DC converter subsequent to deactivating the DC/DC converter when the voltage level across the low-voltage bus is less than a predetermined third voltage less than the predetermined second voltage.