Low Voltage Energy Harvesting by an Efficient AC-DC Step-Up Converter

In this paper, a direct ac-to-dc power converter is proposed for efficient energy harvesting from the low voltage inertial micro generators. The conventional power converters use diode bridge rectifiers and condition the micro generator outputs in two stages. Hence, they are inefficient and may not be a feasible option for very low voltage micro generators. Moreover, they are not conducive for optimum energy harvesting. The proposed converter avoids the use of bridge rectifiers, and directly converts the ac input to the required dc output. This converter uses a boost converter and a buck-boost converter to process the positive and negative half cycles of the ac input voltage, respectively. Furthermore, using this converter, maximum energy harvesting can be implemented effectively. Analysis of the converter is carried out. Based on the analysis, two schemes are proposed to control the converter. Design guidelines are presented for selecting the converter component and control parameters. A self-starting circuit is proposed for independent operation of the converter. Simulation results are presented to validate the proposed converter topology and control scheme.