A Generalized Series-Connected Multilevel Inverter (MLI) Based on Reduced Power Electronic Devices for Symmetrical/Asymmetrical Sources

Multilevel inverter (MLI) has grown rapidly in recent years to achieve higher voltage levels, lower voltage stress of the power switches, and lower harmonic distortion of the inverter voltage. The proposed work emphasizes the design of a generalized multilevel inverter using symmetrical and asymmetrical DC sources at the input. The merit of the proposed MLI can efficiently reduce the power electronic devices to produce the output voltage and generate seven-level using 7 power switches, whereas generating 11, 13, and 15-level using ten power switches only. Proposed MLI can be expanded in a cascaded fashion, reducing complexity, and size and thus significantly improving inverter cost and performance. With some newly developed topologies, a wide range of comparisons are made in order to prove the performance of the proposed MLI. Besides, the total standing voltage and the level-to-switch ratio are estimated to show the effectiveness of the proposed inverter further, and the parameters are compared with the newly developed MLI topologies. A multicarrier pulse width method, as well as a low-frequency modulation technique, is adopted to generate the desired gate pulses of the IGBT switches using the DSPACE-1103-based controller. A laboratory prototype of the proposed seven-level, 11-level, 13-level, and 15-level inverters is developed, and the experimental results of the MLIs at different loading or voltage conditions are presented. Further, the inverter losses, efficiency, and the %THD are also analyzed and compared with the other topologies.