Patent ID: 6603675
Filing Date: 2003-08-05
Classification: H02M,Y02B

Abstract:
An apparatus for converting direct voltage into a three-phase alternating voltage and conversely comprising: a VSC-converter having a direct voltage intermediate link with a positive pole and a negative pole and at least one phase leg interconnecting the two poles and having at least two current valves connected in series, each current valve having at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith, the apparatus further comprising a transformer with two opposite ends of a first winding thereof connected to an output each of the VSC-converter and with a second winding thereof connected to an arrangement adapted to form voltage pulses for forming a three-phase alternating voltage, the apparatus also comprising a unit adapted to control the VSC-converter and said arrangement for obtaining said voltage conversion, wherein the VSC-converter comprises at least one snubber capacitor connected to said current valves thereof, that said arrangement comprises a direct converter having at least three phase legs connected through the opposite ends thereof to opposite ends of said second winding of the transformer and having at least two current valves connected in series, each of these current valves being able to conduct current and block voltage in both directions and to turn on by gate control, and that the midpoints of said phase legs of the direct converter are provided with phase outputs for forming a terminal for said alternating voltage between these phase outputs.