High step down multilevel resonant buck converter with high voltage ratio

This paper presents a type of converter working with high voltage and used for high step down voltage reduction. The converter can be used as the core for the construction of a Power Electronic Transformer (PET). A Single-Star Bridge Cells Modular Multilevel Cascade Converter (MMCC) is used to create a AC/DC or DC/DC converter with high step down voltage ratio. The converter uses LLC resonant converters to transfer the energy from the MMCC cells to the load. Despite the idea to use modular converters for the construction of PET is not new, in the classical PET the control is in charge of the cell voltage balancing and for the second stage the load sharing regulation. The proposed converter can work with a more simple control ensuring the load sharing and the voltage balancing thanks the property of parallelized LLC resonant converters. The work reports simulation results with main parameter variations.