Converter and a method for controlling a converter
First Claim
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1. A converter comprising:
- a series connection of at least two current valves (2, 3) arranged between two poles (4, 5), a positive and a negative, of a direct voltage side of the converter, each of which current valves comprising at least one circuit (12) provided with a semiconductor component (13a, 13b) of turn-off type and a rectifying component (14a, 14b) connected in anti-parallel therewith, an alternating voltage phase line (11) being connected to a mid-point (10), denominated phase output, of the series connection between two current valves while dividing the series connection into two equal parts (1a, 1b),a resonant circuit (16) comprising snubber capacitors (15), which are connected in parallel with a respective one of the semiconductor components (13a, 13b) of turn-off type of the current valves, and at least one inductor (17) and an auxiliary valve (18) provided with semiconductor components (20a, 20b) of turn-off type for recharging said snubber capacitors (15) in connection with a commutation of the phase current, anda control device (24) for controlling the turn-on and turn-off of the semiconductor components (13a, 13b) of turn-off type of the current valves, wherein the converter comprises a device (31) for measuring the derivative (dI/dt) of the current through the current valves (2, 3), and a detection device (32) co-operating with said measuring device (31) for detecting a short-circuit in the converter, the detection device (32) being adapted to detect a short-circuit current when the current derivative (dI/dt) measured by the measuring device (31) is equal to or exceeds a stipulated current derivative limit value (dI/dtlim) during a length of time exceeding a stipulated time limit value (tlim).
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Abstract
The invention relates to a converter provided with a resonant circuit (16), which converter comprises a device (31) for measuring the derivative (dI/dt) of the current through the current valves 82, 3) and a detection device (32) co-operating with said measuring device (31) for detecting a short-circuit in the converter, the detection device (32) being adapted to detect a short-circuit current when the current derivative (dI/dt) measured by the measuring device (31) is equal to or exceeds a stipulated current derivative limit value (dI/dtlim) during a length of time exceeding a stipulated time limit value (tlim). The invention also relates to a method for controlling such a converter.
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Citations
33 Claims
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1. A converter comprising:
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a series connection of at least two current valves (2, 3) arranged between two poles (4, 5), a positive and a negative, of a direct voltage side of the converter, each of which current valves comprising at least one circuit (12) provided with a semiconductor component (13a, 13b) of turn-off type and a rectifying component (14a, 14b) connected in anti-parallel therewith, an alternating voltage phase line (11) being connected to a mid-point (10), denominated phase output, of the series connection between two current valves while dividing the series connection into two equal parts (1a, 1b), a resonant circuit (16) comprising snubber capacitors (15), which are connected in parallel with a respective one of the semiconductor components (13a, 13b) of turn-off type of the current valves, and at least one inductor (17) and an auxiliary valve (18) provided with semiconductor components (20a, 20b) of turn-off type for recharging said snubber capacitors (15) in connection with a commutation of the phase current, and a control device (24) for controlling the turn-on and turn-off of the semiconductor components (13a, 13b) of turn-off type of the current valves, wherein the converter comprises a device (31) for measuring the derivative (dI/dt) of the current through the current valves (2, 3), and a detection device (32) co-operating with said measuring device (31) for detecting a short-circuit in the converter, the detection device (32) being adapted to detect a short-circuit current when the current derivative (dI/dt) measured by the measuring device (31) is equal to or exceeds a stipulated current derivative limit value (dI/dtlim) during a length of time exceeding a stipulated time limit value (tlim). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for controlling a converter, which converter comprises:
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a series connection of at least two current valves (2, 3) arranged between two poles (4, 5), a positive and a negative, of a direct voltage side of the converter, each of which current valves comprising at least one circuit (12) provided with a semiconductor component (13a, 13b) of turn-off type and a rectifying component (14a, 14b) connected in anti-parallel therewith, an alternating voltage phase line (11) being connected to a mid-point (10), denominated phase output, of the series connection between two current valves while dividing the series connection into two equal parts (1a, 1b), a resonant circuit (16) comprising snubber capacitors (15), which are connected in parallel with a respective one of the semiconductor components (13a, 13b) of turn-off type of the current valves, and at least one inductor (17) and an auxiliary valve (18) provided with semiconductor components (20a, 20b) of turn-off type for recharging said snubber capacitors (15) in connection with a commutation of the phase current, and a control device (24) for controlling the turn-on and turn-off of the semiconductor components (13a, 13b) of turn-off type of the current valves, wherein the derivative (dI/dt) of the current through the current valves (2, 3) is measured and compared with a current derivative limit value (dI/dtlim), a short-circuit current being detected when the measured current derivative (dI/dt) is equal to or exceeds the current derivative limit value (dI/dtlim) during a length of time exceeding a stipulated time limit value (tlim). - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification