A Multi-Port Converter for Energy-Harvesting Systems

In energy-harvesting storage systems, in order to guarantee the correct operation and integration of its parts into the system, different power converters must be used. Using several stages increases energy processing and therefore decreases the overall efficiency of the system. In this paper, an integrated multi-port converter with galvanic isolation is proposed. It allows the transfer of energy between the solar panel, the battery, and the user using the fewest possible stages, thus maximizing efficiency. Operating in three modes depending on the battery’s state of charge, solar radiation and load conditions, the converter can conduct electric power between its ports. The proposal was validated in a 1 kW prototype performing the different modes of operation. It should be noted that a PV emulator (ETS150X5.6C-PVF) was used in the experimental setup; by means of this device, conditions such as solar irradiance and temperature, which affect the energy generation of PV panels, were controlled. In addition, the transformer employed in the prototype implementation was handmade; therefore, its design could be improved to obtain better performance. The experimental results show efficiencies exceeding 94%, and an analysis of the distribution of losses in the circuit was carried out. Also, a comparison with previous proposals is presented, showing competitive features.