A Seven-Level Hybrid Inverter with DC-Link and Flying Capacitor Voltage Balancing

Hybrid Multi-Level Inverter(MLI) topologies are gaining attention over conventional ones due to their extended applications in the power, industrial and renewable energy sectors. MLIs are optimized which can provide compact size, reduced cost and higher efficiency compared to the conventional types. In this paper, a hybrid structure of novel three-phase seven-level inverter is proposed. This topology is a combination of cascade-connected two-level cells and H-bridge cells with flying capacitors (FCs). The operating principle and the balancing technique for the DC-link capacitors and FCs are also presented. The generation of various output voltage levels using Sinusoidal Pulse Width Modulation (SPWM) is presented. The comparative analysis is carried out to show the number of components in the proposed circuit configuration and their voltage ratings are considerably lower compared to the conventional and recently proposed topologies. The performance of the proposed topology is verified with simulation studies and also in the experimentation. The simulation and experimental results validate the effectiveness of the proposed topology and the control technique.