Comparative Analysis of Active Capacitor Voltage Balancing Method for Flying Capacitor Multilevel Converters

This paper presents a comparative analysis of an active capacitor voltage balancing method for Flying Capacitor Multilevel (FCM) converters, focusing on the effectiveness of various strategies in maintaining optimal capacitor voltages. We examine both natural balancing methods and active control methods, evaluating their performance under a variety of operational scenarios. An active balancing method based on an Overall Priority Index (OPI) is utilized, which optimizes the selection of switching states to minimize voltage deviations from nominal values. An analysis of the proposed method is conducted using simulations on a five-level FCM and a six-level converter, to compare its performance with that of existing methods. OPI-based methods reduce capacitor voltage ripple, as demonstrated in the results. Various experimental results are presented to demonstrate the stability of the proposed method under various conditions of load and modulation index.