High-frequency Quasi-Z-source Inverter Concept for Short-circuit Capable GaN-HEMT-based Converters

This paper proposes to apply GaN-HEMTs to quasi-Z-source inverters (qZSIs). The qZSIs can cover the poor short-circuit capability of GaN-HEMTs owning to the inductors in the impedance-source of qZSIs because the inductor limits shoot-through current. From the theoretical analysis, a design procedure of the inductance is considered under the both conditions of the normal operation and the short-circuit fault protection. Short-circuit tests with GaN-HEMTs are conducted in short-circuit fault equivalent circuits of both a voltage-source inverter (VSI) and qZSI. Experiments demonstrate that the qZSI could reduce the power dissipation in a GaN-HEMT during a load short-circuit fault by 98.5% and increase the short-circuit tolerance of the inverter to longer than 4 μs. As a result, qZSIs can extend application range of GaN-HEMTs.