Pulse-frequency modulation (PFM) as an efficient method for charging a supercapacitor in a medium power solar application

This thesis investigates the role of maximum power point tracking (MPPT) using switched-mode DC-DC converters in solar energy harvesting/storage systems utilizing supercapacitors. The goal is determining the optimum method of transferring energy to the supercapacitor and gaining insight into the issues involved in such systems.;Models of a supercapacitor, solar panel, buck converter and MPPT system employing pulse-frequency modulation (PFM) were developed using MatLab/Simulink. Circuitry was designed and constructed to verify the theoretical analysis. The results show that while MPPT provides maximum energy over most of the range of the supercapacitor charge cycle, it does not when the supercapacitor is nearly discharged.;The results also show that MPPT improves energy transfer by only a few percent when the supercapacitor voltage approaches the maximum power point voltage of the solar panel.;The results are significant relative to current research in integrating solar panels and supercapacitors into stand-alone energy harvesting/storage systems.