This paper presents the analysis, design and implementation of a closed-loop adaptive multistage switched-capacitor converter (AMSCC) for step-down conversion applied to piezoelectric energy harvesting. Its power part consists of two cascaded sub-circuits: (i) Front: a bridge rectifier with a filter capacitor ([Formula: see text]), and (ii) Core: five-stage serial-parallel SC step-down converter with an output capacitor ([Formula: see text]). This rectifier converts piezoelectric AC source into DC type, and [Formula: see text] captures/stores the energy to build a supply [Formula: see text], and then the serial-parallel SCC transforms [Formula: see text] into five different levels as: [Formula: see text]/5, [Formula: see text]/4, [Formula: see text]/3, [Formula: see text]/2, or [Formula: see text] to charge the battery load. By using the proposed phase generator, a proper level can be manipulated adaptively according to the recent supply and battery voltages for realizing an adaptive multistage charging procedure. Such an adaptive multistage operation is helpful not only to protect the usage of battery, but also to handle the supply variation of piezoelectric device. Some theoretical analysis and design include: formulation, steady-state analysis, stability, capacitance selection, and multistage output response/power. Finally, the performance of AMSCC scheme is simulated and verified experimentally on the implemented prototype circuit, and the results are illustrated to show the efficacy of this scheme.
Piezoelectric Energy Harvesting Solutions: A Review
