Vsc-converter

• US 20040052023A1
• Filed: 09/29/2003
• Published: 03/18/2004
• Est. Priority Date: 12/20/2000
• Status: Abandoned Application

• Current Assignee: ABB AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Asplund, Gunnar
• Application Number:
  US10/451,256
• Publication Number:
  US 20040052023A1
• Time in Patent Office: Days
• US Class Current: 361/91.1
• CPC Class Codes: H02H 7/1222 responsive to abnormalities in the input circuit, e.g. transients in the DC input
• CPC Class Codes: H02M 1/348 Passive dissipative snubbers
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4833 Capacitor voltage balancing
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H03K 17/08144 in thyristor switches
• CPC Class Codes: H03K 17/08148 in composite switches
• CPC Class Codes: H03K 17/107 in composite switches

Abstract

A VSC-converter for converting direct voltage into alternating voltage and vice versa, comprising several current valves (1; 10-13), each current valve comprising a semiconductor element (2) of turn-off type and a first rectifying member (3) connected in anti-parallel therewith. At least one of the current valves is provided with a circuit for over voltage protecting connected in parallel with the current valve, which circuit comprises a series connection of a surge arrester (5) and a second rectifying member (6), the second rectifying member (6) being connected in anti parallel with the first rectifying member (6) being connected in anti parallel with the first rectifying member (3) included in said at least one current valve. The invention also relates to a VSC-converter where each of the series connected circuits (30) that build up the current valves of the converter comprises, in at least one of the current valves, a surge arrester (5) connected in parallel with a capacitor (33) included in the circuit (30) and in series with a rectifying component (34) included in the circuit (30).

Claims

1. A VSC-converter for converting direct voltage into alternating voltage and vice versa, comprising several current valves (1), each current valve comprising a semiconductor element (2) of turn-off type and a first rectifying member (3) connected in anti-parallel therewith, characterized in that at least one of the current valves is provided with a circuit for over voltage protection connected in parallel with the current valve (1), which circuit comprises a series connection of a surge arrester (5) and a second rectifying member (6), the second rectifying member (6) being connected in anti-parallel with the first rectifying member (3) included in said at least one current valve.

3. A VSC-converter according to any of the preceding claims, characterized in that a capacitor (8) is connected in parallel with the surge arrester (5) and in series with the second rectifying member (6) in the respective circuit.

4. A VSC-converter according to any of the preceding claims, characterized in that the surge arrester (5) is a zinc oxide surge arrester.

5. A VSC-converter according to any of the preceding claims, characterized in that said second rectifying member (6) is a diode, preferably a free wheeling diode.

2. A VSC-converter for converting direct voltage into alternating voltage and vice versa, which comprises a series connection of at least four current valves (10-14) arranged between two poles (14, 15), a positive and a negative, of a direct voltage side of the converter, each current valve comprising a semiconductor element (2) of turn-off type and a first rectifying member (3) connected in anti-parallel therewith, and an alternating voltage phase line (20) connected to a first midpoint (19), denominated phase output, of the series connection between two current valves while dividing the series connection into two equal parts, the series connection having a second midpoint (22) between two of said current valves of one of the parts of the series connection, said second midpoint (22) being connected via a flying capacitor (23) to a, with respect to the phase output, corresponding second midpoint (24) of the other part of the series connection, characterized in that the current valves (10, 13) connected between one (14) of the poles and said second midpoint (22) of one of the parts of the series connection and between the other pole (15) and said second midpoint (24) of the other part of the series connection each comprises a circuit for over voltage protection connected in parallel with the current valve (10, 13), which circuit comprises a series connection of a surge arrester (5) and a second rectifying member (6), the second rectifying member (6) of the respective circuit being connected in anti-parallel with the first rectifying member (3) included in the current valve over which the circuit is connected.

6. VSC-converter for converting direct voltage into alternating voltage and vice versa, comprising several current valves, each current valve consisting of several series connected circuits (30), said circuits each comprising a semiconductor component (31) of turn-off type, a first rectifying component (32) connected in anti-parallel therewith, a capacitor (33) connected in parallel with the semiconductor component (31) of turn-off type, and a second rectifying component (34) connected in series with the capacitor (33), in parallel with the semiconductor component (31) of turn-off type and in anti-parallel with the first rectifying component (32), characterized in that each of the series connected circuits (30) of at least one of the current valves comprises a surge arrester (5) connected in parallel with said capacitor (33) and in series with said second rectifying component (34).

7. A VSC-converter according to claim 6, characterized in that the surge arrester (5) is a zinc oxide surge arrester.