Combined T-type and NPC Seven-Level Boost Active Neutral Point Clamped Inverter for Medium Voltage Applications

This paper has proposed a hybrid seven-level inverter topology with a boosting capability three times that of conventional seven-level inverter topologies. It contains ten number of active switches and an internal flying capacitor unit that develops a composition like the combination of T-type and neutral point clamped (NPC) inverter topologies. The proposed inverter topology increases dc link voltage utilization and reduces the total standing voltages across the power switches. In addition, self-voltage balancing of the floating capacitor is achieved through a simple level shifted PWM modulation technique. The dc link requirement of the proposed inverter topology is reduced by 66% when compared to the conventional seven-level inverters, and it can be more useful in industrial applications, including grid-tied renewable generation units. The working methodology and steady state analysis of the topology are presented, and its operation is validated through the simulation results performed in both Matlab/Simulink and PSIM platforms. In addition, experimental results verify the proposed inverter topology.