Topological and Modulation Design of Three-Level Z-Source Inverters

This paper presents the development of two three-level cascaded Z-source inverters, whose output voltage can be stepped down or up unlike a traditional buck three-level inverter. The proposed inverters are designed using two three-phase voltage-source inverter bridges, supplied by two uniquely designed Z-source impedance networks and cascaded at either their DC sides to form a DC-link-cascaded Z-source inverter or AC outputs using single-phase transformers to form a dual Z-source inverter. For controlling both inverters, various modulation schemes are designed with their performances verified experimentally using an implemented laboratory prototype