Power supply system for a motor vehicle having a low-voltage onboard power supply and having a higher-voltage onboard power supply

• US 20020050742A1
• Filed: 06/11/2001
• Published: 05/02/2002
• Est. Priority Date: 06/10/2000
• Status: Active Grant

• Current Assignee: BMW AG (Bayerische Motoren Werke AG)
• Original Assignee: BMW AG (Bayerische Motoren Werke AG)
• Inventors: Schumann, Anton, Grom, Alfred, Pfab, Xaver, Kapfhammer, Karl
• Granted Patent: US 6,693,368 B2
• Time in Patent Office: Days
• US Class Current: 307/9.1
• CPC Class Codes: H02H 3/202 for dc systems
• CPC Class Codes: H02J 7/1423 with multiple batteries

Abstract

A power supply system for a motor vehicle has a low-voltage onboard power supply and a higher-voltage onboard power supply. Either the minus connection or the plus connection of at least the high-power consuming devices of the higher-voltage onboard power supply is coupled via a central bus line with the corresponding (minus or plus) connection of the low-voltage onboard power supply. The central bus line is provided with a controllable switch. Devices are provided for measuring the voltage of the low-voltage onboard power supply, and/or for measuring the differential current between the current flowing on the plus line and the current flowing on the minus line in the higher-voltage onboard power supply. The controllable switch is opened when the voltage in the low-voltage onboard power supply has exceeded a defined voltage threshold and/or when the differential current has exceeded a defined current threshold.

Claims

1. A power supply system for a motor vehicle having a low-voltage onboard power supply and a higher-voltage onboard power supply, wherein:

one of the minus connection and the plus connection of at least the high-power consuming devices of the higher-voltage onboard power supply is coupled via a central bus line with the corresponding minus or plus connection of the low-voltage onboard power supply;

the central bus line has a controllable switch;

devices are provided for measuring the voltage of the low-voltage onboard power supply; and

the controllable switch is opened when the voltage of the low-voltage onboard power supply has exceeded a defined voltage threshold.

3. The power supply system according to claim 1, wherein:

a DC/DC converter without potential separation is provided between the higher-voltage onboard power supply and the low-voltage onboard power supply; and

an existing coupling between the minus connection of the high-voltage onboard power supply and the minus connection of the low-voltage onboard power supply in the DC/DC converter is used as the central bus line.

5. Method for supplying electric power to a motor vehicle by means of a power supply system according to one of claims 1 to 3.

2. A power supply system for a motor vehicle having a low-voltage onboard power supply and a higher-voltage onboard power supply wherein:

one of the minus connection and the plus connection of at least the high-power consuming devices of the higher-voltage onboard power supply is coupled via a central bus line with the corresponding minus or plus of the low-voltage onboard power supply;

the central bus line has a controllable switch;

devices are provided for measuring the differential current between the current flowing on the plus line and the current flowing on the minus line in the higher-voltage onboard power supply; and

the controllable switch is opened when the differential current has exceeded a defined current threshold.

4. The power supply system according to claim 2, wherein:

a DC/DC converter without potential separation is provided between the higher-voltage onboard power supply and the low-voltage onboard power supply; and

an existing coupling between the minus connection of the high-voltage onboard power supply and the minus connection of the low-voltage onboard power supply in the DC/DC converter is used as the central bus line.

6. A method of supplying power to a vehicle having a first set of high voltage power consuming devices and a second set of lower voltage power consuming devices, comprising:

providing a higher-voltage onboard power supply coupled to provide electric power to the first set power consuming devices;

providing a lower-voltage onboard power supply coupled to provide electric power to the second set of power consuming devices, with one of a minus connection and a plus connection of at least the first set of power consuming devices being coupled via a central bus line with the corresponding minus or plus connection of the low-voltage onboard power supply;

providing a controllable switch in the central bus line;

measuring the voltage of the low voltage onboard power supply;

opening the controllable switch when the measured voltage exceeds a defined threshold value.

7. A method of supplying power to a vehicle having a first set of high voltage power consuming devices and a second set of lower voltage power consuming devices, comprising:

providing a higher-voltage onboard power supply coupled to provide electric power to the first set power consuming devices;

providing a lower-voltage onboard power supply coupled to provide electric power to the second set of power consuming devices, with one of a minus connection and a plus connection of at least the first set of power consuming devices being coupled via a central bus line with the corresponding minus or plus connection of the low-voltage onboard power supply;

providing a controllable switch in the central bus line;

measuring a differential between current flowing in a line of said bus that is connected to the plus connection and a line of said bus that is connected to the minus connection in the higher-voltage onboard power supply;

opening the controllable switch when the differential exceeds a defined threshold value.

8. In a vehicle power supply system having a low-voltage onboard power supply connected to supply electric power to a set of low-voltage power consuming devices, a higher-voltage onboard power supply connected to supply electric power to a set of higher-voltage power consuming devices, and a central bus line connecting one of a plus connection and a minus connection of at least the higher-voltage power consuming devices with the corresponding plus or minus connection of the low-voltage on board power supply, protective apparatus comprising:

a controllable switch disposed in said central bus line;

devices for measuring at least one quantity selected from the group consisting of voltage of the low-voltage onboard power supply, and a difference between current flowing in a line of said bus that is connected to the plus connection and a line of said bus that is connected to the minus in the higher-voltage onboard power supply; and

opening the controllable switch when a measured quantity exceeds a preset threshold.