A STEP-DOWN SWITCHED-CAPACITOR AC-DC CONVERTER FOR ENERGY HARVESTING SYSTEM USING VIBRATION-BASED ENERGY

摘要

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, an AC-DC converter realizing 1/N× (N = 2,3,...) step-down is designed by using switched-capacitor techniques. Although conventional converters offer a DC output by regulating the stored energy in a big capacitor, the proposed converter generates a DC output by realizing AC-DC conversion. Thus, the proposed converter can improve power efficiency. To clarify effectiveness of the proposed converter, theoretical analysis is performed concerning power efficiency and equivalent circuit. When the AC input is a rectangular-wave voltage, the theoretical results obtained by the theoretical analysis are consistent with SPICE simulated results. Furthermore, SPICE simulation results show that the proposed converter can improve power efficiency about 32 % from the conventional converter when Rl = 100Ω. Next, the validity of the circuit design is confirmed by experiments. The experiments show that the proposed converter can offer stepped-down DC voltage from sinusoidal voltage.