Single-Phase AC–DC–AC Multilevel Converter for Grid Overvoltage Based on an H-Bridge Connected in Series to the Five-Leg Converter

In this work, an ac-dc-ac multilevel power converter for grid overvoltage is investigated. The developed configuration is composed of one single-phase ac-dc-ac three-leg module and two H-bridges. One of them is connected to the shared part of the system to generate multilevel voltages at the input and output of the structure, and the other one is connected to the grid side to compensate the grid overvoltage. The converter can be employed in applications with same input and output frequency, such as uninterrupted power supply and unified power quality conditioner without isolation transformer. System model, a space vector pulsewidth modulation strategy to balance the individual dc-link voltages, and an overall control strategy to adjust the grid power factor, the amplitude, and the frequency of the load voltage are presented. The proposed converter is compared in terms of harmonic distortion and semiconductor losses with conventional structures. Simulation and experimental results demonstrate the operation of the proposed topology.