Abstract: The invention relates to a method for controlling a VSC-converter provided with a resonant circuit (16).

Abstract: The invention relates to a converter provided with a resonant circuit, in which converter the resonant circuit comprises means for detecting a zero current condition in the auxiliary valve. The means is adapted to send to the control device of the converter signals indicating a prevailing zero current condition in the auxiliary valve, and the control device is adapted to allow a turn-off of a semiconductor component of turn-off type of the auxiliary valve only after the receipt by the control device of a signal indicating a prevailing zero current condition in the auxiliary valve. The invention also relates to a method for controlling such a converter.

Abstract: The invention relates to a converter provided with a resonant circuit (16), which comprises a control device (24) adapted, in connection with a commutation of the phase current (iph) from a semiconductor element of turn-off type of a first current valve (2, 3) to a rectifying member of a second current valve (3, 2) to effectuate a turn-on of the auxiliary valve (18) of the resonant circuit with a varaible time delay (td) after the turn-off of the first current valve, the converter comprising a member (35) for determining said time delay in dependence on the magnitude and the direction of the phase current (iph) and the magnitude and the direction of a determined unbalance so that the unbalance is corrected at least partly when the control device applies the time delay (td). The invention also relates to a method for controlling such a converter.

Abstract: The invention relates to a VSC-converter for converting direct voltage into auxiliary voltage and vice versa, which comprises a series connection of at least two current valves (5, 6) arranged between two poles (7, 8), a positive and a negative, of a direct voltage side of the converter, each current valve comprising several series connected circuits (12), each of which circuits comprising a semiconductor component (13) of turn-off type and a rectifying component (14) connected in anti-parallel therewith, an alternating voltage phase line (16) being connected to a midpoint (15), denominated phase output, of the series connection of current valves (5, 6) between two of said current valves while dividing the series connection into two equal parts.

Abstract: A converter has a resonance circuit with an auxiliary valve (18), an inductor (17) and capacitive members (15) for assisting the commutation of the converter. A control arrangement (24) is adapted to control turning-on and turning-off of controllable semiconductor devices of the main valve of the converter and controllable semiconductor components of the auxiliary valve. Means are arranged for measuring the current in the phase output (10) of the converter. When carrying out two subsequent commutation processes for changing the phase potential on the phase output from the potential of a first of the poles of a direct voltage side of the converter to that of a second of the poles and then back to the one of the first pole the second commutation process is started before the first one has been completed.

Abstract: An apparatus for converting direct voltage into three-phase alternating voltage and conversely comprises a VSC-converter (8) having a direct voltage intermediate link (9) and at least one phase leg (12, 13). Each current valve (14-17) of the phase legs has at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith. A transformer (19) has two opposite ends of a first winding (20) thereof connected to an output (21, 22) each of the VSC-converter and a second winding (23) connected to a direct converter having at least three phase legs. Each of the current valves of the direct converter being able to conduct current and block voltage in both directions and to turn on by gate control. The midpoints (27, 27′, 27″) of the phase legs of the direct converters are provided with phase outputs for forming a terminal for the alternating phase voltage between these phase outputs.

Abstract: An apparatus for converting direct voltage into three-phase alternating voltage and conversely comprises a VSC-converter (8) having a direct voltage intermediate link (9) and at least one phase leg (12, 13). Each current valve (14-17) of the phase legs has at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith. A transformer (19) has two opposite ends of a first winding (20) thereof connected to an output (21, 22) each of the VSC-converter and a second winding (23) connected to a direct converter having at least three phase legs. Each of the current valves of the direct converter being able to conduct current and block voltage in both directions and to turn on by gate control. The midpoints (27, 27′, 27″) of the phase legs of the direct converters are provided with phase outputs for forming a terminal for the alternating phase voltage between these phase outputs.

Abstract: An apparatus for converting direct voltage into alternating voltage and conversely comprises a VSC-converter (8) having a direct voltage intermediate link (9) and at least one phase leg (12, 13). Each current valve (14-17) of the phase legs has at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith. A transformer (19) has two opposite ends of a first winding (20) thereof connected to an output (21, 22) each of the VSC-converter and a second winding (23) connected to a direct converter having at least one phase leg. Each of the current valves of the direct converter being able to conduct current and block voltage in both directions and to turn on by gate control. A midpoint (27) of the phase leg of the direct converter is provided with a phase output for forming a terminal for the alternating phase voltage between this output and a further phase output (28).

Abstract: An apparatus for converting direct voltage into alternating voltage and conversely comprises a VSC-converter (8) having a direct voltage intermediate link (9) and at least one phase leg (12, 13). Each current valve (14-17) of the phase legs has at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith. A transformer (19) has two opposite ends of a first winding (20) thereof connected to an output (21, 22) each of the VSC-converter and a second winding (23) connected to a direct converter having at least one phase leg. Each of the current valves of the direct converter being able to conduct current and block voltage in both directions and to turn on by gate control. A midpoint (27) of the phase leg of the direct converter is provided with a phase output for forming a terminal for the alternating phase voltage between this output and a further phase output (28).