Modular High-Power DC-DC Converter for MVDC Renewable Energy Collection Systems

Medium-voltage (MV) dc collection system is a promising solution for future integration of large-scale renewables at remote places. This requires a high-power dc-dc converter to step up the voltage and connect with the high voltage direct current transmission line. In this article, a novel modular high-power dc-dc converter is proposed, with the combination of half-bridge and full-bridge submodules (SMs), as well as thyristors and diodes. It alternatively configures the SMs into parallel connection with the MV side to effectively share high current stress while series connection with the high voltage side to share the high voltage stress. It presents attractive features such as high device utilization rate, low cost, high step-up ratio, high efficiency, and small footprint. The circuit structure, operation principle, and the control schemes are discussed. Simulation results demonstrate the effectiveness, and the experimental results from a scaled down prototype further prove the proposed concept.