A single stage AC/DC converter for low voltage energy harvesting

In this paper, a novel ac/dc converter is proposed for low voltage, low power rectification applications. The proposed converter manages the energy harvested from micro-scale electromagnetic transducers. It integrates the conventional Boost and Buck-Boost topologies with a shared inductor, a bidirectional switch and two split filtering capacitors. The Boost and the Buck-Boost topologies function in the positive and negative half input cycles, respectively. The inductor is energized by being shorted with the input source through the MOSFET channel without using the diodes. This enables active rectification of low amplitude (below 0.7 V) ac voltages. Theoretical analysis, design considerations and control method are detailed. A 45 mW circuit prototype, which converts a 0.4 V peak, 100 Hz ac voltage to 3.3 V dc is designed and tested to verify the proof of concept.