Development of an energy router for DC nanogrid-based building applications

Recent energy router (ER) research has primarily focused on high-voltage DC systems and regional microgrid clusters, enabling energy exchange among large-scale photovoltaics (PV), energy storage systems (ESS), and grid infrastructures; however, compact low-voltage (LV) ERs for in-building DC distribution remain underexplored despite the need for fine-grained power control and integration of localized resources. This paper proposes a modular multi-port ER tailored for building-level DC nanogrids, where distributed PV, ESS, and diverse DC loads are coordinated under real-time control within installation-space constraints. The proposed ER employs a USB-C power delivery (PD) interface, enabling simultaneous transmission of over 200 W power and 10 Gbps data through a single cable, while achieving over 98% conversion efficiency and supporting autonomous bidirectional power flow with integrated protection and battery management. A 50 kW nanogrid living lab comprising 255 nodes, including 51 hardware ER units and 204 software-defined nodes, was developed for validation. Experimental results under realistic conditions-including renewable intermittency, islanded operation, dynamic load variation, and plug-and-play events-demonstrate stable operation and effective energy coordination, highlighting the feasibility of LVDC ER-based nanogrids as a scalable solution for future building energy systems.