Method and device for detecting a direct-current fault current

Patent metadata

Field	Value
Publication number	US-10640000-B2
Application number	US-201515509347-A
Country	US
Kind code	B2
Filing date	Jul 2, 2015
Priority date	Sep 8, 2014
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

The invention relates to a method for detecting a direct-current fault current in an electrical alternating-current circuit, wherein a rectifier unit (14) is connected to an alternating-current network (34) by means of a primary side (13) and provides a direct current on a secondary side (15) and wherein the alternating-current network (34) is protected by means of a fault-current circuit breaker (38), which interrupts the circuit if an alternating-current fault current greater than a specified alternating-current tripping threshold occurs. A direct-current fault current on the primary side (13) is measured and is compared with a specified direct-current tripping threshold. An alternating-current fault current is produced if the direct-current fault current lies above the tripping threshold. The invention further relates to a device (10) for detecting a direct-current fault current and to a charging apparatus (12) comprising such a device (10).

First claim

The invention claimed is:

1. A method for detecting a direct current fault current in an alternating current electric circuit, wherein a rectifier unit ( 14 ) having a primary side ( 13 ) is connected to an alternating current network ( 34 ) and provides a direct current on a secondary side ( 15 ), and wherein the alternating current network ( 34 ) is fuse-protected with a fault-current circuit-breaker ( 38 ) which interrupts the circuit if an alternating current fault current greater than a specified alternating current tripping threshold arises, comprising the following steps:
a) measuring a direct current fault current on the primary side ( 13 ),
b) comparing the direct current fault current with a specified direct current tripping threshold and
c) generating an alternating current fault current if the direct current fault current lies above the tripping threshold, the current intensity of the alternating current fault current having been chosen so that it lies above the alternating current tripping threshold of the fault-current circuit-breaker,

wherin the direct current is used as charging current for charging an energy storage device ( 42 ), and an alternating current fault current is generated when the energy storage device ( 42 ) has been fully charged.

2. The method as claimed in claim 1 , characterized in that the alternating current fault current according to step c) is generated by the additional connection of a resistor ( 22 ) on the primary side ( 13 ).

3. The method as claimed in claim 1 , characterized in that an alternating current fault current is generated for the purpose of checking the operational capability of the fault-current circuit-breaker ( 38 ).

4. The method as claimed in claim 1 , characterized in that a malfunction of the fault-current circuit-breaker ( 38 ) is inferred if the primary side ( 13 ) is not disconnected from the voltage source after generation of the alternating current fault current.

5. A charger ( 12 ) for charging an energy storage device ( 42 ) of a vehicle ( 40 ), including a device ( 10 ) for detecting a direct current fault current in an electric circuit, including a measuring unit ( 16 ) for measuring a direct current fault current, characterized in that the device ( 10 ) includes a tripping unit ( 18 ) which has been set up to generate an alternating current fault current in the presence of a direct current fault current that is greater than a specified direct current tripping threshold, wherein the charger ( 12 ) is configured to generate an alternating current fault current when the energy storage device ( 42 ) has been fully charged.

6. The charger ( 12 ) as claimed in claim 5 , characterized in that the charger ( 12 ) includes a compensating device which is configured to compensate a direct current fault current by generating a further direct current fault current having identical current intensity but having opposite current direction.

7. The charger ( 12 ) as claimed in claim 5 wherein the charger ( 12 ) charges an energy storage device ( 42 ) of a vehicle ( 40 ).

Assignees

• Bosch Gmbh Robert

Inventors

• Eckert Bernd
• Eppler Steffen

Classifications

• B60L3/0069 Primary

  relating to the isolation, e.g. ground fault or leak current · CPC title

• H02H3/332

  with means responsive to DC component in the fault current · CPC title

• Y02T90/14

  Plug-in electric vehicles · CPC title

• B60L3/04

  Cutting off the power supply under fault conditions (protective devices and circuit arrangements in general H01H; H02H) · CPC title

• H02H3/334

  with means to produce an artificial imbalance for other protection or monitoring reasons or remote control (H02H3/338 takes precedence) · CPC title