Loss Distribution Analysis of a Three-Port Converter for Low-Power Stand-Alone Light-to-Light Systems

In locations far from the equator achieving high conversion efficiency in low-power solar systems is challenging due to low solar irradiance levels. This paper presents a high efficiency three-port converter (TPC) for light-to-light (LtL) applications where no direct solar conversion is required. The separation of the power flows allows to replace the conventional solution of two cascaded converters into a single structure with shared components.

A loss distribution analysis of the proposed structure is performed, which shows very good match with the experimental results. A prototype of the TPC demonstrates high efficiency in both power flow paths. At low irradiation level, the power flow from the photovoltaic panel to the battery shows a peak efficiency of 99.1% at at 1.5 W output power, and the LED driver stage presents a peak efficiency of 97.3% at 3 W output power.