Family of Current-fed Switched Capacitor –based Modular DC Transformer Topologies for HVDC Interconnection Application

Dc transformer (DCT) is a key device to build the high-voltage dc (HVDC) power networks. In this paper, three DCT topologies based on the current-fed switched capacitor (CFSC) structure are proposed for HVDC systems interconnection. Comparing with the conventional dual-active-bridge (DAB) –based DCT scheme, the proposed solutions not only reserve the advantages but also have the proper switched capacitor voltage self-balance characteristic, redundant submodule design, fault ride-through capability and flexible control. These merits increase the reliability, efficiency and economic benefit of DCT and decreases the manufacturing difficulty. The comprehensive experimental results validate the effectiveness and correctness of the proposed solutions.