Implementation of Hybrid GSA SHE Technique in Hybrid Nine-Level Inverter Topology

The recent trend in multilevel inverters (MLIs) is to produce the high quality staircase ac voltage waveform while utilizing the optimum number of switching devices. In this context, this article presents a combination of topological and modulation scheme-based solution for the optimum performance of MLI. A concept of adaptable dc voltage link in conjunction with modified H-bridge unit is introduced to reduce the number of switching devices. Further to improve the quality of voltage waveform and to reduce the switching losses in the proposed topology, a hybrid gravitational search algorithm (GSA) selective harmonic elimination (SHE) technique is proposed and implemented on the newly developed MLI topology with symmetric dc sources. Comparative analysis is performed with the conventional and existing hybrid cascaded MLI topologies, which exhibits the superiority of the proposed topology in terms of reduction in count of switching devices, count of components, and conduction losses. The efficacy of the proposed hybrid GSA SHE technique is shown in the simulated results. The feasibility of the proposed MLI topology and SHE technique is further verified by the experimental results of a nine-level inverter with both equal and unequal dc sources.