A Self-Sensing Synchronous Electric Charge Extraction (SECE) Solution for Piezoelectric Energy Harvesting Enhancement

In piezoelectric energy harvesting (PEH), the harvesting capability can be enhanced by using the synchronous electric charge extraction (SECE) interface circuit. The charge extraction actions are carried out when the vibration displacement, or equivalently the piezoelectric voltage, attains its extreme values. Sensing and peak detection are two necessary functions supporting synchronous charge extraction. In the previous studies, these functions were realized by using an external displacement sensor or a self-powered voltage peak detector. In this paper, a new self-sensing SECE solution is proposed. The sensing function is implemented simultaneously based on the switching actions of the buck-boost type SECE circuit under strong discontinuous conduction mode (DCM) operation. Peak detection is realized by analyzing the changing trend of the sensed piezoelectric voltage with a micro-controller. Different from the previous self-contained SECE solutions, this design samples the vibration information throughout a whole cycle, rather than merely telling the peak positions. It gives more degrees of freedom for the design and implementation of the synchronized switch control towards more robust and adaptive solutions for PEH enhancement.