| Abstract: |
Multilevel inverters (MLIs) are the key power-electronic interface for converting the direct-current (DC) power generated by variable renewable sources, in particular photovoltaic (PV) arrays and wind turbines, into grid-quality alternating-current (AC) power. This paper presents a comprehensive review and a quantitative meta-analysis of past work on the design and optimization of high-efficiency multilevel inverters for renewable energy applications. A systematic search of IEEE Xplore, Scopus, Web of Science, and ScienceDirect identified peer-reviewed studies published between 2000 and 2025, which were screened and coded for topology family, modulation strategy, optimization algorithm, validation method, and reported performance metrics; a total of 62 studies were included in the meta-analysis. Across all sampled designs, switching-angle schemes optimized with metaheuristic algorithms, including the genetic algorithm, particle swarm optimization, grey wolf optimizer, and their hybrids, consistently reduced total harmonic distortion (THD) by between 3.2 and 41.6 percent relative to conventional sinusoidal pulse-width-modulation baselines, while efficiency gains over unoptimized single-stage two-level converters ranged from 1.8 to 6.4 percentage points. Cascaded H-bridge topologies dominate low- and medium-power PV systems because of their modular structure, string-level maximum power point tracking, and low switching losses, whereas neutral-point-clamped and T-type configurations are preferred where a low component count and neutral-point balance are critical. The paper also synthesizes the evidence on voltage-stress reduction, soft-switching techniques, and digital-twin and hardware-in-the-loop validation practices, and it identifies the methodological gaps, notably the scarcity of published experimental validation and the absence of standardized efficiency metrics, that future research should address. |
