Cost-effective single-source 25-level inverter achieving twelvefold voltage gain with redundant switching and hybrid modulation

This study introduces a 25-level inverter powered by a single DC source that achieves a twelvefold voltage gain using fifteen switches, four diodes, and four capacitors. The main novelty of the proposed inverter lies in the integrated co- design of a high-gain switched-capacitor topology with intrinsic redundant switching states (RSS) and a dedicated hybrid modulation framework for their effective exploitation. The circuit is arranged so that the maximum blocking voltage (MBV) across each device does not exceed half of the peak output voltage (0.5Vmax), which helps lower the inverter’s total cost. The specific arrangement of the proposed topology generates RSS at certain levels. To exploit this feature, a hybrid pulse-width modulation (HPWM) method is developed, which incorporates redundant states to minimize the longest continuous discharge periods (LDP) of the capacitor. This HPWM scheme combines level- shifted PWM for output voltage synthesis and phase-shifted PWM only within the redundant-state regions, thereby improving capacitor voltage balancing without increasing the effective switching burden of the main power path. Consequently, the capacitor voltage ripple is significantly reduced, and the inrush charging current is effectively limited, resulting in lower losses. Also, since fewer devices are activated and placed in the load current path at each output level, the conduction losses of the structure are minimized. The proposed inverter is analyzed in terms of its configuration, switching states, capacitor sizing, and loss performance. A comprehensive comparison with other switched-capacitor multilevel inverters (SCMLI) is carried out across multiple evaluation parameters, demonstrating the superior performance of the proposed structure. Additionally, a practical cost analysis confirms the economic advantage of the inverter, attributed to lower device voltage stress and the reduced cost and volume of capacitors. To validate the theoretical studies, a laboratory prototype has been implemented, and both steady-state and dynamic tests confirm the correct operation and effectiveness of the proposed inverter.