Startup Strategy with Constant Peak Transformer Current for Hybrid Multilevel Energy Router

Energy Router has received lots of attention in a great amount of applications due to its powerful functionality and great flexibility. Capacitor charging strategy plays a key role in the operation of energy router. The focus is on the submodule applied in the hybrid multilevel energy router in this paper. The submodule is constituted of a three-level rectifier and an isolated DC-DC converter in which a three-level converter and an H-bridge converter are respectively used in the primary and secondary side of the high frequency transformer. The mentioned situations cause the complexity of the startup process. This paper proposes a mathematical model of charging process for a single submodule as well as a startup strategy with the key feature of constant peak transformer current, which performs well on both peak charging current and charging time. In the energy router, all submodules have identical structure and share the same strategy. The proposed startup strategy can also be applied to other energy routers with similar topologies. Both the mathematical model and the startup strategy have been verified by simulations.