A high-frequency 1.5 MVA H-bridge building block for cascaded multilevel converters using emitter turn-off thyrister

This paper proposes a 1.5 MVA H-bridge building block (HBBB) using the newly developed emitter turn-off (ETO) thyristor to demonstrate the superior performance of the ETO. The modular HBBB is intended to be used in high-power cascaded multilevel voltage source converters for reactive power compensation applications. Because of theirs identical layouts, the HBBB are easily manufactured for both the building block itself and for the whole system. Whenever the power requirement of the system needs to be changed, the HBBBs are simply added into or taken away from the system without redesigning the HBBB component ratings. The hardware configuration as well as component selection and design of the HBBB are presented. This paper also proposes the new air-core snubber inductor design, which lowers losses and is lighter in weight than the conventional iron-core inductor. An ETO-based 1.5 MVA HBBB prototype has been implemented and tested in inverter mode. Experimental results indicate that the proposed ETO-based HBBB with the snubber components operates effectively at high frequency and high power.