Multi-voltage vehicle electrical supply system for a motor vehicle and method for operating the same

• US 8,076,794 B2
• Filed: 05/23/2008
• Issued: 12/13/2011
• Est. Priority Date: 11/25/2005
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Proebstle, Hartmut, Roesler, Michael, Merwerth, Joerg, Christ, Thomas
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): Fauth, Justen
• Application Number:
  US12/126,417
• Publication Number:
  US 20080284246A1
• Time in Patent Office: 1,299 Days
• Field of Search: None
• US Class Current: 307/9.1
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A multi-voltage vehicle electrical system for a motor vehicle is provided, including at least one multi-voltage generator, a first energy store, whose energy may be fed into a first low-voltage vehicle electrical system branch having low-voltage consumers, and a second energy store, whose energy may be fed into a second high-voltage vehicle electrical system branch having high-voltage consumers, as well as at least one controllable switching device, using which the energy generated by the multi-voltage generator may be distributed to the first and the second vehicle electrical system branches, the first and the second energy stores being connected in series to one another and the first vehicle electrical system branch being connected to a node between the first and the second energy store and to a reference potential of the first energy store.

Claims

1. A multi-voltage vehicle electrical system for a motor vehicle, comprising:

at least one multi-voltage generator;

a first energy store, whose energy is fed into a first low-voltage vehicle electrical system branch having low-voltage consumers;

a second energy store, whose energy is fed into a second high-voltage vehicle electrical system branch having high-voltage consumers; and

a controllable switching device, using which the energy generated by the multi-voltage generator is distributed to the first and the second vehicle electrical system branches,

wherein the first and the second energy stores are connected in series to one another and the first vehicle electrical system branch is connected to a node between the first and the second energy stores and to a reference potential of the first energy store,

wherein the second vehicle electrical system branch is connected in parallel to the series circuit made of first and second energy stores,

wherein the controllable switching device being switchable between a first circuit configuration, in which the multi-voltage generator is in parallel to the first energy store and to the first vehicle electrical system branch, and a second circuit configuration, in which the multi-voltage generator is in parallel to the series circuit made of first and second energy stores and to the second vehicle electrical system branch,

wherein the first energy store is a battery and the second energy store is a super capacitor circuit,

wherein the controllable switching device comprises a first switchable interrupter between the terminal node of the first vehicle electrical system branch and the terminal of the multi-voltage generator facing away from its reference potential, and

wherein the first interrupter is opened when the charge state of the second energy store has fallen below a predetermined charge level, and the second energy store is charged when the first interrupter is opened.

2. The multi-voltage vehicle electrical system according to claim 1, wherein the controllable switching device further comprises a diode, which is connected between the terminals of the multi-voltage generator and the second energy store facing away from the respective reference potentials such that if the first interrupter is closed, no current flows from the second to the first energy store.

3. The multi-voltage electrical system according to claim 1, wherein the controllable switching device further comprises a second switchable interrupter, which is connected between the terminals of the multi-voltage generator and the second energy store facing away from the respective reference potential such that if the first interrupter is closed, a current flow from the second to the first energy store is prevented by opening the second interrupter.

4. The multi-voltage vehicle electrical system according to claim 1, further comprising a third energy store, which is connected in a cascade with the first and second energy stores and the multi-voltage generator.

5. A method for operating a multi-voltage vehicle electrical system including a multi-voltage generator delivering a selectable output voltage, a first energy store and a second energy store connected in series thereto, a first low-voltage electrical system branch connected in parallel to the first energy store, and a second high-voltage vehicle electrical system branch connected in parallel to the series circuit made of first and second energy stores, and a controllable switching device, using which the multi-voltage generator may alternatively be switched parallel to the first energy store or parallel to the series circuit made of first and second energy stores, wherein the controllable switching device comprises a first switchable interrupter between a terminal node of the first vehicle electrical system branch between first and second energy stores and the terminal of the multi-voltage generator facing away from its reference potential and a unidirectional disconnection unit, between the terminals of the multi-voltage generator and the second energy store facing away from their particular reference potentials, the method comprising the acts of:

preventing a current flow from the second to the first energy store if the first interrupter is dosed; and

before the first interrupter is closed, equalizing the generator output voltage to the potential of the terminals of the first energy store facing away from its reference potential,

wherein the first energy store is a battery and the second energy store is a super capacitor circuit, and

wherein the first interrupter is opened when the charge state of the second energy store has fallen below a predetermined charge level, and the second energy store is charged when the first interrupter is opened.

6. The method according to claim 5, wherein the disconnection unit is designed as a second switchable interrupter.

7. The method according to claim 6, wherein, before the generator output voltage is equalized, the second interrupter is opened.

8. The method according to claim 7, wherein, before the second interrupter is closed, the first interrupter is first opened and the generator output voltage is equalized to the potential at the terminals of the second energy store facing away from its reference potential.

9. The method according to claim 6, wherein before the second interrupter is closed, the first interrupter is first opened and the generator output voltage is equalized to the potential at the terminals of the second energy store facing away from its reference potential.

10. The method according to claim 9, wherein, before the first interrupter is opened, the generator output voltage is equalized to the potential at the terminal of the first energy store facing away from its reference potential.

11. The method according to claim 6, wherein the second energy store is designed as a capacitor circuit having high capacitance and the multi-voltage generator is activated after the first interrupter is opened to generate a voltage ramp for charging the capacitor circuit.

12. The method according to claim 5, wherein the first interrupter is opened in recuperation operation.

13. The method according to claim 5, wherein the second energy store is designed as a capacitor circuit having high capacitance and the multi-voltage generator is activated after the first interrupter is opened to generate a voltage ramp for charging the capacitor circuit.