Integrated Three-Port DC-DC Converter for Photovoltaic (PV) Battery Stand-alone Systems

Several power sources such as PV solar arrays and battery are often used to manage the
power flow for a photovoltaic (PV) based stand-alone power system due to the fluctuation
nature of solar energy resource, and deliver a continuous power to the users in an
appropriate form. Traditionally, three different single-input single-output (SISO) dc/dc
converters would have been used. To reduce the cost and improve the power density of the
system, an integrated three-port isolated dc/dc converter is proposed in this paper. It can
realize all functions of the energy delivery due to the fluctuation nature of solar energy.
Moreover, a novel transformer configuration enables variable turns ratio controlled by the
phase between the two current excitations subjected to the primary windings, allowing a
wider input/output range. 1 kW experimental prototype has been built to demonstrate a wellmanaged
power flow for PV and battery stand-alone system.