Experimental comparison of two-level full-SiC and three-level Si-SiC Quasi-Z-source inverters for PV applications

Abstract

The paper presents a comparative study of two solar string inverters based on the quasi-Z-source (QZS) network. The first solution comprises a full-SiC two-level QZS inverter, while the second design was built based on a three-level neutral-point-clamped QZS inverter with Silicon based Metal-Oxide-Semiconductor Field-Effect Transistors (Si MOSFETs). Several criteria were taken into consideration: the size of passive elements, thermal design and size of heatsinks, voltage stress across semiconductors, and efficiency investigation. The photovoltaic (PV)-string rated at 1.8 kW power was selected as a case study system. The advantages and drawbacks of both solutions are presented along with conclusions.