Current limiter

Patent metadata

Field	Value
Publication number	US-9791876-B2
Application number	US-201414782785-A
Country	US
Kind code	B2
Filing date	Feb 18, 2014
Priority date	Apr 12, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A current limiter for selectively limiting a rate of change of current in a DC electrical network may include a first electrical block including an inductive element and a second electrical block including a bidirectional switch. The first electrical block is connected in parallel with the second electrical block between first and second terminals, and the first and second terminals are connectable to the DC electrical network. The bidirectional switch is switchable to: (1) a first mode to permit current flow through the second electrical block in a first current direction and at the same time inhibit current flow through the second electrical block in a second, opposite current direction; and (2) a second mode to permit current flow through the second electrical block in the second current direction and at the same time inhibit current flow through the second electrical block in the first current direction.

First claim

The invention claimed is:

1. A current limiter for selectively limiting a rate of change of a fault current in a DC electrical network, the current limiter comprising:
a first electrical block including an inductive element; and
a second electrical block including a bidirectional switch, the first electrical block being connected in parallel with the second electrical block between first and second terminals, the first and second terminals being connectable to the DC electrical network,
wherein the bidirectional switch is switchable to a first mode to permit current flow through the second electrical block in a first current direction and at a same time inhibit current flow through the second electrical block in a second current direction, the first and second current directions being opposite to each other, and the bidirectional switch is switchable to a second mode to permit current flow through the second electrical block in the second current direction and at a same time inhibit current flow through the second electrical block in the first current direction, and
wherein the current limiter further includes a controller to control the switching of the bidirectional switch to each of the first and second modes, and the controller is configured to selectively control the switching of the bidirectional switch to either of the first and second modes while a fault current is flowing through the current limiter, to enable the second electrical block to form a current path that allows current to freewheel around a loop formed by the first and second electrical blocks and thereby allows the fault current to fall at a higher rate than it would do in the absence of the current path.

2. The current limiter according to claim 1 wherein the bidirectional switch is switchable to a blocking mode to inhibit current flow through the second electrical block in the first and second current directions.

3. The current limiter according to claim 1 wherein the second electrical block further includes a resistive element for dissipating energy.

4. The current limiter according to claim 1 wherein the bidirectional switch includes a bidirectional controlled thyristor and/or a bidirectional gas discharge switch.

5. The current limiter according to claim 1 wherein the bidirectional switch includes a pair of inverse-parallel-connected switching elements or a plurality of series-connected pairs of inverse-parallel-connected switching elements, each inverse parallel-connected switching element including a first switching sub-element, each first switching sub-element including at least one first active switching device.

6. The current limiter according to claim 5 wherein each first active switching device is an active switching device with reverse blocking capability.

7. The current limiter according to claim 1 wherein the bidirectional switch includes a pair of inverse-series-connected switching elements, each inverse series-connected switching element including a second switching sub-element, each second switching sub-element including at least one second active switching sub-device.

8. The current limiter according to claim 5 wherein each switching sub-element includes a plurality of series-connected active switching devices.

9. The current limiter according to claim 7 wherein each second active switching device is an active switching device without reverse blocking capability.

10. The current limiter according to claim 7 further including a plurality of passive current check elements, each passive current check element including at least one passive current check device, each of the plurality of passive current check elements being connected in inverse-parallel with a respective one of the second switching sub-elements or with a respective one of the second active switching devices.

11. The current limiter according to claim 10 wherein each passive current check element includes a plurality of series-connected passive current check devices.

12. The current limiter according to claim 1 wherein the controller is configured to control the switching of the bidirectional switch to inhibit current flow through the second electrical block in one of the first and second current directions when a voltage across the bidirectional switch changes from a zero voltage to a voltage having a positive voltage direction relative to that current direction.

13. The current limiter according to claim 1 wherein the controller is configured to control the switching of the bidirectional switch to the first or second mode upon a voltage generated across the inductive element changing from opposing a rise in a current flowing therethrough to maintaining the current flowing therethrough.

14. The current limiter according to claim 1 wherein the controller is configured to control the switching of the bidirectional switch to switch to the first mode upon a voltage across the bidirectional switch changing to a second voltage with a positive voltage direction relative to the first current direction when the voltage across the bidirectional switch changes to the second voltage from a first voltage with a negative voltage direction relative to the first current direction.

15. The current limiter according to claim 14 wherein the controller further includes a control circuit for transmitting a control signal to switch the bidirectional switch, the control circuit including an energy storage device that is arranged to be chargeable by the first voltage, wherein the control circuit is configured to transmit the control signal to switch the bidirectional switch upon the energy storage device reaching a predefined charge level.

16. The current limiter according to claim 15 wherein the energy storage device is configured to reach the predefined charge level when the voltage across the bidirectional switch changes to the second voltage.

17. The current limiter according to claim 1 wherein the controller is configured to control the switching of the bidirectional switch to switch to the second mode upon a voltage across the bidirectional switch changing to a second voltage with a positive voltage direction relative to the second current direction when the voltage across the bidirectional switch changes to the second voltage from a first voltage with a negative voltage direction relative to the second current direction.

Assignees

• Alstom Technology Ltd
• General Electric Technology Gmbh

Inventors

• Davidson Colin Charnock

Classifications

• H02H9/047

  Free-wheeling circuits · CPC title

• G05F1/59 Primary

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02H3/025

  Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection · CPC title

• H01H9/547

  Combinations of mechanical switches and static switches, the latter being controlled by the former · CPC title

• H02H9/001

  limiting speed of change of electric quantities, e.g. soft switching on or off (progressive control of electronic switches for eliminating interferences H03K17/16) · CPC title