Design and Experimental Study of a GaN-based Three-Port Multilevel Inverter

A three-port multilevel inverter with two DC ports and an AC port using Flying Capacitor Multilevel (FCML) design based on Gallium Nitride (GaN) switches is proposed in this paper. Recently, FCML inverter has shown a superior ability for power conversion with high power density, improved Total Harmonic Distortion (THD), and efficiency. The presented three-port multilevel inverter fits various applications such as battery and photovoltaic (PV) grid integration and standalone AC load. The proposed inverter is experimentally verified by building a 3-kW prototype using GaN switches which include two 4-level FCML converter paths, each share the same bus capacitor (C bus ), which links them together. One FCML path is 1 kW that incorporates an unfolder for the DC-to-AC conversion and has achieved a peak efficiency of 98.2% with AC voltage and current THDs of 1.26% and 1.23%, respectively. While the second FCML converter path is 2 kW used for the DC-to-DC conversion and has achieved a 99.43% peak efficiency.