Design of a Step-Down AC-DC Converter for Energy Harvesting System Using Vibration-Based Energy

To realize battery-free operation employing energy harvesting, a step-down switched-capacitor-based converter has been used as a vibration-to-electricity converter. In this paper, to improve power efficiency, a step-down ACDC converter realizing 1/N (N=2,3,... ) conversion modes is designed by using switched-capacitor techniques. Although conventional converters offer an output by regulating the stored energy in a big capacitor, the proposed converter generates the output by performing AC-DC conversion. Thus, the proposed converter can improve power efficiency. Concerning the power efficiency, the effectiveness of the proposed converter is clarified by theoretical analysis. Furthermore, the validity of the circuit design is confirmed by simulations and experiments.