A Bidirectional Isolated Multiport DC-DC Converter for DC grid

Abstract

Multiport DC/DC converters (MPC) is becoming a promising configuration to integrate DC grids with different voltage levels. This paper presents a neutral-point clamped (NPC) converter-based MPC (NMPC), which is developed to interconnect medium voltage DC (MVDC) grid and low voltage DC (LVDC) grid. The circuit topology and operation principle of NMPC is first introduced. The soft-switching operation based on zero-voltage switching (ZVS) is developed to reduce switching loss. Simulation verification is implemented to validate the proposed MPC. The proposed NMPC may perform independent bidirectional power flow control among different ports without using decoupling algorithms. The proposed NMPC enables high voltage operation due to the application of 3-level converter. The power characterization of the NMPC is simple, which is beneficial to realize the decoupling power flow control among the interconnected DC ports.