Asymmetric reduced switch cascaded multilevel inverter with improved efficiency

This paper presents a novel 15-level asymmetric Multilevel Inverter (MLI) topology designed for high-performance power conversion in renewable energy systems. The proposed inverter utilizes an innovative arrangement of three DC sources in a 1:2:4 voltage ratio, coupled with a unique switching strategy, to generate a near-sinusoidal output voltage with minimal harmonic distortion. The MLI’s structure comprises a full-bridge configuration augmented by three half-bridge cells, optimizing the trade-off between component count and output voltage quality. A comprehensive theoretical analysis of the inverter’s operation, including switching states and harmonic content, is presented. The prototype implementation employs isolated DC voltage sources, FPGA-based control logic, and dedicated driver circuits for each switch. Experimental results demonstrate the inverter’s capability to produce a 15-level output voltage waveform with a Total Harmonic Distortion (THD) of just 4.52%. Efficiency analysis reveals excellent performance across various load conditions, with peak efficiencies of 98%, 97.5%, and 97% for resistive, lightly inductive, and highly inductive loads, respectively. The inverter maintains high efficiency over a wide range of output power, showcasing its versatility. Detailed harmonic spectrum analysis and individual switch voltage waveforms corroborate the theoretical predictions.This MLI topology offers a compelling solution for applications demanding high power quality and efficiency, particularly in grid-connected renewable energy systems. The findings suggest significant potential for further development and scaling of this asymmetric MLI design for higher power applications.