1 MHz cascaded Z-source inverters for scalable grid-interactive photovoltaic (PV) applications using GaN device

This paper presents a scalable cascaded Z-source inverter for residential PV systems with high efficiency and high switching frequency. The commercial low voltage Gallium Nitride (GaN) device with low loss and high frequency is used to facilitate each Z-source inverter cell modular. The comprehensive Z-source network is designed based on the innovative equivalent AC circuit model. A detailed efficiency analysis is applied to a 3kW single phase grid-connected PV system with four cascaded Z-source inverter cells and 1MHz output frequency. The proposed topology also has the advantage to achieve independent maximum power point tracking (MPPT) control for each module and therefore improve the PV energy harvesting capability.