Multiple Charge Extractions with Bias-flip Interface Circuit for Piezoelectric Energy Harvesting

In piezoelectric energy harvesting (PEH), synchronous electric charge extraction (SECE) has the benefit of load independence. To reduce the energy dissipation on parasitic resistance, multi-shot SECE (MCE) was implemented to split the charge extraction process. In this paper, a multiple charge extraction with bias-flip (MCEBF) interface circuit is proposed. It not only reduces the dissipation in charge extraction but also enlarges the extractable energy of piezoelectric structure by adding a bias-flip action. MCEBF can also generate positive and negative voltage rails via buck-boost topology to supply power for double-rail devices. The analytical and experimental comparison among SECE, MCE, and MCEBF under different controls are also provided. In experiments, MCEBF offers a 57.3% improvement over SECE and 24% over MCE, in terms of harvested power.