Search

International audience; Grid connection of remote offshore wind-parks uses high-voltage direct current technology and in order to reduce costs and losses and maximize profitability, semiconductor power losses must be minimized. To properly choose the semiconductors, it is necessary to estimate their losses for a large number of operating conditions. This article deals with a modelling approach to calculate power losses for many such operating conditions, based on measured semiconductor characteristics and the chosen multilevel modulation strategy.The case of the integrated gate-commutated thyristor is considered because, for a given device rating, it is possible to select an integrated gate-commutated thyristor benefitingfrom the best trade-off between on-state losses and turn-off losses, thus minimising the power losses of the two end-stations.

Utilization of the Integrated Gate Commutated Thyristor as a semiconductor switch in the Series Resonant Converter for isolated medium voltage DC-DC conversion offers an opportunity for high conversion efficiency while operating at the high switching frequency. Low conduc- tion losses of the switch as well as decreased switching losses due to zero-voltage turn-on and low current turn-off in the sub-resonant operating regime are reflected in the efficiency increase of the converter. This paper explores the switching behavior of the semiconductor device under low currents while giving insight into the achievable turn- off energy losses and duration of the turn-off transients, as information required during the design process of series resonant converter. Experimental measurements confirm trends observed with simulation results related to turn- off delay process, providing further understanding of the switching losses and achievable performances under resonant mode of operation.

Series connected IGCTs find application in hard-switched commercial power converters at the MW power levels. Expanding the application of these devices to medium voltage dc-dc resonant converters is of great interest due to the IGCTs low conduction losses. This requires a deeper understanding of the devices behaviour in series connection and under switching conditions different than those in hard switched converters. In particular, the voltage sharing between series connected IGCTs must be achieved with significantly reduced turn-off currents, typical for resonant converters. Relying on a versatile IGCT test setup, this paper explores the operational performances of series connected IGCT operation at very low turn-off current and with snubber capacitance in the range of a few tens of nF. The results presented in the paper are obtained from commercially available 4:5 kV 68mm reverse conducting IGCTs (with standard irradiation), as well as two customized engineering samples (high irradiated variants), optimized on their technology curve for high switching frequencies. The IGCTs are successfully operated in series connection at 5 kHz, with device voltage being effectively shared in resonant converter operation.