Design and Simulation of a Nine Level Inverter with Less Switches Operating in Stand-Alone and Grid-Connected Modes
This paper presents a single-phase nine-level (9L) inverter configuration which can be suitable for grid-connected renewable energy systems. The proposed inverter is realized using a T-type neutral point-clamped inverter connected in series to a flying capacitor (FC) H-bridge. A self-voltage balancing based on superfluous switching state is developed and integrated with PWM controller, which is responsible for constrain the FC voltage at one-fourth of the input dc source voltage. The advance PWM technique employs the generation of 9L waveform without using any voltage sensor, thereby reducing the complicacy of the overall control scheme. In comparison to conventional and recent configurations, generation of the 9L waveform using a lower number of components is the notable contribution. Furthermore, a compendious comparison study is included which confirms the merits of the proposed inverter against those of other state-of-the art topologies. Finally, simulation results are included for validating the feasibility of the proposed system.
Keywords - Flying Capacitor, Nine-Level Inverter, Power Quality, Sensorless Voltage Control.