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This paper discusses switching performance and power losses of silicon carbide (SiC) Metal-Oxide Semiconductor Field-Effect Transistors in a high-frequency quasi-Z-source inverter operating at unity power factor. Basic types of switching processes are distinguished and precisely analyzed. Necessity for using deadtime in impedance-source converters is explained. Shoot-through states with one, two, and three phase legs are investigated and observed processes, such as an unintentional “snubber effect” of nonswitched MOSFET s, are described for the first time. As a result of this analysis, a novel modulation method with minimum number of hard-switching transitions is developed. All discussed aspects are illustrated with experimental results of a 100-kHz/6-kW quasi-Z-source inverter built with SiC elements. The newly developed method is compared with other state-of-the-art methods, and the result is that even for high voltage boost (B = 1.9) losses are reduced by 1%, and efficiency reaches 97% at nominal conditions. At inductive power factor, the developed method also outperforms the other methods.