New high-gain micro photovoltaic inverter based on GaN

Microinverters have been widely used in distributed photovoltaic (PV) systems in recent years due to their modularity and flexibility. However, the current development of microinverter topologies faces significant challenges, such as low voltage gain and limited reliability. To solve these problems, an enhanced switched-inductor quasi-Z-Source inverter (ESL-qZSI) based on gallium nitride high electron mobility transistor (GaN HEMT) is proposed in this work. The proposed inverter introduces a novel topology that integrates an auxiliary boost unit with a switched-inductor quasi-Z-source network. This topology significantly enhances the voltage gain at low shoot-through duty ratios and reduces the voltage stress across the switching device. Additionally, the use of GaN HEMT as power switching components increases the switching frequency from the traditional 10 kHz to 100 kHz, in which a specialized negative turn-off gate driver circuit is designed to adapt the characteristics of the GaN HEMT and to ensure reliable switching operation. This increase in frequency reduces the size of passive components, such as inductors. Experimental results show that the proposed inverter achieves a boost factor of 5.75 at a shoot-through duty ratio of 0.2, which indicates that its performance is improved by 15% and 91% greater than the traditional switched-inductor-capacitor quasi-Z-source inverter (SLC-qZSI) and the traditional switched-inductor Z-source inverter (SL-ZSI), respectively. These results confirm that the proposed inverter enhances the voltage gain of existing topologies. Besides, compared with SLC-qZSI, the proposed inverter can obtain a higher efficiency of 90.5%, which shows the advantage of efficiency. In conclusion, the proposed ESL-qZSI with GaN HEMT provides a hopeful solution for high-efficiency and compact microinverter systems in photovoltaic applications.