Comparison of photovoltaic converter configurations for wearable applications

Wearable electronics is an emerging area and power converters for wearable applications are also in development. This paper focuses on wearable applications powered by photovoltaic (PV) cells, specifically a bag able to charge mobile electronics. In wearable applications, illumination on each PV cell may vary significantly and the resulting system efficiency depends on the configurations of the PV cells and converters. Through this research, the system efficiencies of five configurations are compared for nine realistic test cases. The five configurations are: series, parallel, cascaded converters, series differential power processing (DPP) converters, and parallel DPP converters. The nine test cases are composed of an ideal case (all PV cells at 1,000 W/m²) and eight realistic illumination cases based on the weather (sunny or cloudy) and realistic usage scenarios. Based on these cases the system efficiency is calculated for each configuration considering a range of converter efficiencies (70% to 100%). Results show that the parallel DPP configuration shows the highest system efficiency in all cases. The average system efficiency for all cases was 99.4% using the parallel DPP configuration, assuming 85% converter efficiency. Among the five configurations, parallel DPP is the most promising configuration for wearable charging applications.