A 3-Phase Supercapacitor Based Single-Source MLI with Self-Voltage Balancing and Boosting Ability

This paper presents a new 3-phase multilevel inverter (MLI) based on a supercapacitor (SC) unit, which is ideal for medium and low-voltage grid-feeding photovoltaic (PV) applications since it is built to deliver nine different output voltage (line-to-line) levels from a single isolated dc source. Two SC units are utilized in each phase to create virtual dc sources while providing self-voltage balancing for the SCs. As a result, no extra control complexity is required compared to conventional neutral point clamped (NPC), flying capacitor (FC) or any other series connected capacitor-based inverter topologies. The proposed MLI is designed such a way that, the SCs could boost the output voltage up to four times than the input dc voltage. The MATLAB/Simulink computer simulation environment and a preliminary experimental prototype setup are used to verify the performance of the proposed MLI.