A New Isolated AC-DC Power Converter Topology with Reduced Number of Switches for High-Input Voltage and High-Output Current Applications

The main objective of this research work is to develop a new low-cost isolated three-level ac-dc power converter topology that is suitable for applications having high input ac voltages and high output currents; for example, hybrid (ac-dc) microgrids or offshore wind farms. Existing three-level converter topologies convert ac power to dc power while maintaining requirements set by international standards for power conversion. These types of converters have significant conduction losses due to high currents in the low-voltage side and high costs, particularly when using several devices in series or in parallel to achieve high-voltage and high-power levels. The proposed topology replaces the conventional three-level converters in the low-voltage side by only two controlled devices and four diodes while still maintaining the basic functionality of a three-level converter. Simulation results for a 87.5-kW case study and experimental results on a 250-W scale-down prototype demonstrate the feasibility of the proposed ideas.