Study on the Control Strategy of Multi-port Power Router

Abstract

In recent years, there has been increasing interests in energy Internet. This paper mainly contributes to the energy router, the core device in the energy Internet. This article adopts AC/DC/AC three-stage structure, which is composed of modular multilevel converter (MMC), dual active bridge (DAB) converter, and three-phase full bridge inverter through the public DC bus to form the main topology of the energy router. And it contains multiple ports of high-voltage DC, low-voltage DC, and low-voltage AC, which is convenient for various forms of load access and realizes plug-and-play function. Research and design a hierarchical decoupling control scheme to simplify the control architecture while achieving independent and flexible control at all stages. In addition, for the input stage MMC structure, the capacitor voltage balance control of each sub-module, the bridge arm energy balance control strategy and the circulating current suppression strategy are designed to achieve the stability of the MMC output DC voltage and suppress the circulating current to a certain extent. Aiming at the topological structure in which multiple DAB units adopted input in series and output in parallel to the intermediate isolation stage, a parallel current sharing control strategy is designed to reduce the impact of parameter differences. Finally, the simulation results are verified by Matlab/Simulink.