Overvoltage protection for a multivoltage vehicle electrical system

Patent metadata

Field	Value
Publication number	US-9941692-B2
Application number	US-201414909000-A
Country	US
Kind code	B2
Filing date	Jun 27, 2014
Priority date	Jul 30, 2013
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

An overvoltage protection circuit for a first subsystem of a multivoltage vehicle electrical system, in which the first subsystem having a first vehicle electrical system voltage, a second subsystem having a second vehicle electrical system voltage, and an electric machine for supplying the second subsystem. The first system voltage is less than the second system voltage. The overvoltage protection circuit includes a first ground connection for connecting a shared ground potential of the first subsystem, the second subsystem, and the electric machine, an additional second ground connection for connecting a reference ground potential, and a control connection for controlling the electric machine. The overvoltage protection circuit checks whether a ground differential voltage between the first and second ground connections reaches a threshold value, and for reducing the second vehicle electrical system voltage when the ground differential voltage between the first and second ground connections reaches the threshold value.

First claim

What is claimed is:

1. An overvoltage protection circuit for a first subsystem of a multivoltage vehicle electrical system, comprising:
an overvoltage protection circuit arrangement configured to check whether a ground differential voltage between a first ground connection and a second ground connection reaches a threshold value, and for reducing a second vehicle electrical system voltage when the ground differential voltage between the first ground connection and the second ground connection reaches the threshold value;
wherein the vehicle electrical system includes the first subsystem having a first vehicle electrical system voltage, a second subsystem having the second vehicle electrical system voltage, and an electric machine for supplying the second subsystem, the first vehicle electrical system voltage being less than the second vehicle electrical system voltage, and includes a first ground connection for connecting a shared ground potential of the first subsystem, the second subsystem, and the electric machine, and an additional second ground connection for connecting a reference ground potential, and a control connection for controlling the electric machine.

2. The overvoltage protection circuit of claim 1 , wherein the overvoltage protection circuit includes a passive overvoltage protective element which is connected between the first ground connection and the second ground connection.

3. The overvoltage protection circuit of claim 1 , wherein the overvoltage protection circuit includes a comparator which is connected to the first ground connection and to the second ground connection on the input side.

4. The overvoltage protection circuit of claim 1 , wherein the overvoltage protection circuit is configured for reducing the voltage generated by the electric machine when the ground differential voltage between the first ground connection and the second ground connection reaches the threshold value.

5. The overvoltage protection circuit of claim 1 , wherein the overvoltage protection circuit is configured for separating a connection between the second subsystem and the electric machine when the ground differential voltage between the first ground connection and the second ground connection reaches the threshold value.

6. The overvoltage protection circuit of claim 1 , further comprising:
a communication connection which is connectable to a communication line to output control instructions to at least one component for one or both of the first and second subsystem(s).

7. The overvoltage protection circuit of claim 6 , wherein the second ground connection is an integral part of the communication connection.

8. A multivoltage vehicle electrical system, comprising:
a first subsystem having a first vehicle electrical system voltage;
a second subsystem having a second vehicle electrical system voltage;
an electric machine for supplying the second subsystem, wherein the first vehicle electrical system voltage is less than the second vehicle electrical system voltage; and
an overvoltage protection circuit configured to check whether a ground differential voltage between a first ground connection and a second ground connection reaches a threshold value, and for reducing the second vehicle electrical system voltage when the ground differential voltage between the first ground connection and the second ground connection reaches the threshold value;
wherein the vehicle electrical system includes the first ground connection for connecting a shared ground potential of the first subsystem, the second subsystem, and the electric machine, and an additional second ground connection for connecting a reference ground potential, and a control connection for controlling the electric machine, and
wherein the first ground connection of the overvoltage protection circuit is connected to a shared ground potential of the first subsystem, the second subsystem, and the electric machine, and the second ground connection is connected to a reference ground potential.

9. A method for protecting a first subsystem of a multivoltage vehicle electrical system from an overvoltage, the method comprising:
reducing the second vehicle electrical system voltage when a ground differential voltage between a shared ground potential of the first subsystem, a second subsystem, and an electric machine and a reference ground potential reaches a threshold value;
wherein the vehicle electrical system includes the first subsystem having a first vehicle electrical system voltage, the second subsystem having a second vehicle electrical system voltage, and the electric machine for supplying the second subsystem, the first vehicle electrical system voltage being less than the second vehicle electrical system voltage.

10. The method of claim 9 , wherein the voltage generated by the electric machine is reduced when the ground differential voltage reaches the threshold value.

11. The method of claim 10 , wherein at least one of the following is performed: (i) operation of the electric machine is alternated between a motor mode and a generator mode, and (ii) a rolling, phase short circuit of the electric machine is carried out when the ground differential voltage reaches the threshold value.

12. The method of claim 9 , wherein a connection between the second subsystem and the electric machine is separated when the ground differential voltage reaches the threshold value.

13. The method of claim 9 , wherein electrical consumers are used in the second subsystem for reducing the voltage.

14. A non-transitory computer readable medium having computer-executable components, which is executable by a processor, comprising:
a program code arrangement having program code for protecting a first subsystem of a multivoltage vehicle electrical system from an overvoltage, by performing the following:
reducing the second vehicle electrical system voltage when a ground differential voltage between a shared ground potential of the first subsystem, a second subsystem, and an electric machine and a reference ground potential reaches a threshold value;
wherein the vehicle electrical system includes the first subsystem having a first vehicle electrical system voltage, the second subsystem having a second vehicle electrical system voltage, and the electric machine for supplying the second subsystem, the first vehicle electrical system voltage being less than the second vehicle electrical system voltage.

15. The non-transitory computer readable medium having computer-executable components of claim 14 , wherein the overvoltage protection circuit includes a passive overvoltage protective element which is connected between the first ground connection and the second ground connection.

Assignees

• Bosch Gmbh Robert
• Seg Automotive Germany Gmbh

Inventors

• Walter Gerhard

Classifications

• G01R31/54

  Testing for continuity · CPC title

• G01R31/006

  on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00) · CPC title

• H02H3/202

  for DC systems · CPC title

• H02H3/36

  involving comparison of the voltage or current values at corresponding points of different systems, e.g. of parallel feeder systems · CPC title

• H02H5/105

  responsive to deterioration or interruption of earth connection (for preventing switching-on H02H11/001) · CPC title