Advancing Power Conversion: A Comprehensive Survey on Reduced Multilevel Inverters, Switching Techniques, And Controllers

Cascaded Multilevel Inverters (CMIs) have become apparent as promising remedies for applications requiring a great deal of power, offering advantages like lower harmonic distortion, higher power handling capacities, and better voltage quality. This survey explores the diverse landscape of switching techniques and controllers employed in cascaded multilevel inverters, aiming to offer a thorough summary of the most recent advancements. First, the survey classifies the different switching methods used in CMIs, for example Space Vector Modulation (SVM), Pulse Width Modulation (PWM), and Selective Harmonic Elimination (SHE). Each technique is examined in terms of its impact on inverter performance, efficiency, and harmonic content in the output waveform. Special attention is given to recent advancements in hybrid and adaptive switching strategies, offering insights into the potential for enhancing inverter operation under varying load conditions. Next, the survey explores the wide variety of controllers used in CMIs, including both closed-loop and open- loop control approaches. Open-loop control strategies, like carrier-based modulation, are analyzed for their simplicity and effectiveness in basic applications. In contrast, closed-loop control strategies, such as Model Predictive Control (MPC) and Proportional-Integral (PI) control, are explored for their ability to regulate output voltage and current precisely, even in dynamic and unpredictable environments. Furthermore, the survey delves into the integration of intelligent control algorithms, like artificial neural networks and fuzzy logic, highlighting their potential in optimizing CMIs for specific applications. The impact of controllers on overall system stability, efficiency, and response time is thoroughly examined.