A Three-Port Energy Router for Grid-Tied PV Generation Systems With Optimized Control Methods

In grid-tied photovoltaic (PV) generation systems, intelligent energy management is required to maximize its performance. In this article, a novel three-port energy router with optimized control is proposed for this application. The proposed converter can interface among three ports (PV source, battery, and dc-link) with high integration. The PV panel is connected to the battery through an interleaved boost structure on the primary side. The primary-side PV-battery system and secondary-side dc-link are connected through a dual-active-bridge (DAB) converter. The battery operates as an energy buffer to compensate for the power mismatch due to the intermittent nature of the PV source. According to the daily power profile and intelligent power management between the grid and battery, six operating modes are possible. Optimized control strategies are customized in different operating modes. The maximum-power-point-tracking (MPPT) of the PV panel can be always realized. The zero-voltage-switching (ZVS) condition for all mosfets, reducing circulating current over a wide range, and flexible energy flow among three ports are all taken into considerations in the design. To verify the proposed concept, a 500 W rated prototype is designed. The designed prototype exhibits high efficiency in various operating modes. The experimental results agree well with the theoretical analysis.