Three-Port Converter With Single Coupled Inductor for High Step-Up Applications

The output voltages of renewable energy resources are relatively low for practical applications. Hence, a converter with high voltage gain is needed. This article proposes a high voltage gain nonisolated three-port converter for a renewable energy source with energy storage applications. A coupled inductor with three windings is used for transferring energies among photovoltaic (PV), battery, and the load. When the battery provides energy to the load, two primary windings with opposite polarities are connected in series. Thus, the effective primary turns is reduced for improving the voltage gain. In addition, the energy stored in the leakage inductor is recycled to the output so as to suppress voltage stress on the power switches and improve system efficiency for energy transference from either PV or battery to the load. Both PV and the battery can provide power to the load independently, thus sharing the load power coordinately. The operation principles, steady-state analyses and key parameter design of the proposed topology are then described in detail. Finally, an experimental prototype is implemented to verify the theoretical analyses with PV, battery, and load voltages of 48 V, 24 V, and 200 V, respectively.