Analysis and Modulation Strategy of Asymmetric Cascaded Half-Bridge Multilevel Inverter with Optimized DC Voltage Ratio

Compared with symmetric cascaded multilevel inverters, asymmetric counterparts can generate more voltage levels without additional modules. However, the existing asymmetric cascaded H-bridge multilevel inverters suffer from critical limitations in the DC voltage ratio and module quantity, hindering their scalable deployment in modular power conversion systems. To address these limitations, this paper proposes an asymmetric cascaded half-bridge multilevel inverter with an optimized DC voltage ratio and devises an appropriate modulation strategy for the control of the inverter. The proposed configuration enables flexible selection of the DC voltage ratio and module quantity. Therefore, it not only effectively minimizes the volume of the inverter modules but also preserves the scalability benefit inherent in the cascaded topology, thereby reducing overall system costs and providing enhanced applicability in low- and medium-voltage systems. The correctness and feasibility of both the optimized configuration and the modulation strategy are verified by simulation and experimental results.