Topologies of Isolated Multiport Converters for DC Grid Applications: A Review

An isolated multiport DC/DC converter (MPC) is a functional solution for integrating renewable energy sources, increasing the efficiency of power distribution, and reinforcing DC grids. Although the concept of MPC has been proposed for past two decades, the applications of the MPC are upgrading along with the development of DC grids. This paper presents an overview about the topology of isolated MPCs applied in DC grids. It is dedicated to provide the comprehensive insights in isolated MPCs according to three main aspects in terms of converter configuration, potential application, and control feasibility. According to different applications, this paper classifies MPCs into three categories, including two-level MPC, three-level MPC, and multi-level MPC. Two different configurations of MPCs, multi-winding transformer type and multi-transformer type are discussed. In addition, a comparative analysis is performed in terms of circuit and operation conditions. The key technique problems and potential solutions are discussed. Finally, the future trends for the development of MPC are discussed.