Design of a High-Frequency Improved Current-Fed Quasi Z-Source Inverter based on SiC devices

This paper presents design process of the 6 kVA improved Current-Fed quasi Z-Source Inverter (iCFqZSI) built with Silicon Carbide (SiC) power semiconductor devices. Impedance network is modified in order to reduce voltage stress of the diodes, furthermore, a fourth MOSFET leg is also added to perform shoot-through states with low on-state losses. The inverter is expected to operate as an interface between three-phase grid and battery energy storage. Design is based on a simulation study performed in Saber, which shows detailed operating conditions of the improved impedance network for the switching frequency range between 50 and 300 kHz. Paper deals also with selection of SiC devices - transistors and diodes (including power losses estimation) and their gate drive circuits. Problems related to passive components (inductors and capacitors) of the impedance circuit and the LC-filter are also discussed. Special attention has been paid to a power board and a busbar in order to minimize circuit parasitic components during 3D CAD design procedure.