Patent ID: 8716893

Claim:
An arrangement comprising: a valve in a Voltage Source Converter (VSC); and a control arrangement, wherein said valve comprises one first semiconductor device of turn-off type with a voltage blocking capacity rating of a first, high level and series-connected second semiconductor devices of turn-off type with a voltage blocking capacity rating of a second, lower level, the first semiconductor device is connected in parallel with the series-connected second semiconductor devices, and said control arrangement is configured to switch said valve into a conducting state starting from a forward biased blocking state of the valve by controlling said second semiconductor devices to be turned on and then said first semiconductor device to be turned on with a delay sufficient for the voltage across said valve to fall to a fraction of less than 10% of the voltage across the valve in said forward biased blocking state of the valve and at the end of the conducting state to turn off said first semiconductor device in advance of turning said second semiconductor devices off, where said second semiconductor devices are turned off by said control arrangement after a majority of recombinations of charge carriers in said first semiconductor device has taken place.