Method for Controlling a Vehicle Electric System

• US 20080211453A1
• Filed: 05/15/2008
• Published: 09/04/2008
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: PRZYWECKI, Frank
• Granted Patent: US 8,076,908 B2
• Time in Patent Office: Days
• US Class Current: 320/104
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method for controlling the electrical system of a motor vehicle with a generator, a battery to supply the electrical system, at least one load and a storage capacitor for brief supply of electrical power on demand, during which the battery is charged when the generator produces excess electrical power is provided. The load is supplied and the battery and the storage capacitor are charged by the generator in load operation or fuel cutoff. The load is additionally supplied by the battery and/or the storage capacitor when the instantaneous generator power is not sufficient. An instantaneously required electrical load power in load operation or fuel cutoff is recorded the load power is compared with an idle power of the generator, and the storage capacitor is charged by the generator when the idle power of the generator is less than the load power in load operation or fuel cutoff.

Claims

1. A method for controlling an electrical system of a motor vehicle with a generator, a battery to supply the electrical system, at least one load and a storage capacitor for brief supply of electrical power on demand, in which the battery is charged when the generator produces excess electrical power, comprising the acts of:

supplying the at least one load and charging the battery and the storage capacitor by the generator during load operation or fuel cutoff;

supplying the at least one load by at least one of the battery and the storage capacitor when the instantaneous generator power is below a threshold;

recording an instantaneously required electrical load power in load operation or fuel cutoff;

comparing the load power with the idle power of the generator; and

charging the storage capacitor by the generator when the idle power of the generator is less than the load power in load operation or fuel cutoff.

2. The method according to claim 1, wherein the storage capacitor is charged by the generator, if the idle power of the generator is less than the load power by a predetermined amount.

3. The method according to claim 1, wherein the storage capacitor is charged by the generator during fuel cutoff.

4. The method according to claim 1, wherein the storage capacitor and the battery are charged by the generator when the power that can be maximally transferred from the generator to the storage is less than the difference between the instantaneous power of generator and the load power.

5. The method according to claim 1, wherein follow-up loads and standby loads are supplied by the storage capacitor after engine stop.

6. The method according to claim 1, wherein the battery is charged by the storage capacitor after engine stop.

7. The method according to claim 1, wherein the battery is charged by the storage capacitor when its charge state drops below a threshold value and excess charge is present in the storage capacitor.

8. The method according to claim 1, wherein the method is automatically restarted at predetermined time intervals.

9. The method according to claim 2, wherein the storage capacitor is charged by the generator during fuel cutoff.

10. The method according to claim 2, wherein the storage capacitor and the battery are charged by the generator when the power that can be maximally transferred from the generator to the storage is less than the difference between the instantaneous power of generator and the load power.

11. The method according to claim 2, wherein follow-up loads and standby loads are supplied by the storage capacitor after engine stop.

12. The method according to claim 2, wherein the battery is charged by the storage capacitor after engine stop.

13. The method according to claim 2, wherein the battery is charged by the storage capacitor when its charge state drops below a threshold value and excess charge is present in the storage capacitor.

14. The method according to claim 2, wherein the method is automatically restarted at predetermined time intervals.

15. The method according to claim 3, wherein the storage capacitor and the battery are charged by the generator when the power that can be maximally transferred from the generator to the storage is less than the difference between the instantaneous power of generator and the load power.

16. The method according to claim 3, wherein follow-up loads and standby loads are supplied by the storage capacitor after engine stop.

17. The method according to claim 3, wherein the battery is charged by the storage capacitor after engine stop.

18. The method according to claim 3, wherein the battery is charged by the storage capacitor when its charge state drops below a threshold value and excess charge is present in the storage capacitor.

19. The method according to claim 3, wherein the method is automatically restarted at predetermined time intervals.

20. An electrical system of a motor vehicle, comprising:

a generator;

a battery to supply the electrical system;

a load; and

a storage capacitor for brief supply of electrical power on demand, wherein the battery is charged when the generator produces excess electrical power;

the load is supplied and the battery and the storage capacitor are charged by the generator during load operation or fuel cutoff;

the load is supplied by at least one of the battery and the storage capacitor when the instantaneous generator power is below a threshold; and

the storage capacitor is charged by the generator when the idle power of the generator is less than the load power in load operation or fuel cutoff.