Application of MTO thyristors in current stiff converters with resonant snubbers

This paper addresses the impact of power devices switching characteristics on design and performance of pulsewidth-modulated current stiff converter (CSC) topologies with resonant snubbers. The MOS turn-off (MTO) thyristors were selected for this study due to their high voltage and current ratings, simplified gatedrive circuitry, unity gain turn-off, greatly reduced storage time allowing higher switching frequencies, and reverse voltage blocking capability. The analysis presented in this paper is supported by experimental data obtained from a CSC commutation cell capable of reproducing all the commutation processes in the current stiff converter topologies with active resonant snubbers. Issues involved in the implementation of the commutation cell itself and MTO characteristics relevant for their operation in CSC topologies with resonant snubbers are addressed in detail in this paper.