Analysis of piezoelectric energy harvesting system with tunable SECE interface

Numerous interface circuits have been proposed over the past years to improve the performances of piezoelectric energy harvesting devices. The so-called synchronous electric charge extraction interface (SECE) brought the advantage of harvesting power independently of the load voltage. In counterpart, its performances exhibited sensitivity to the electromechanical coupling. It was shown, in particular, that harvested power was significantly decreased at high coupling. To overcome this drawback, the so-called tunable SECE interface has recently been proposed. Instead of the total charge extraction performed by the original SECE, the tuning method consists in extracting only a portion of the electric charge. This paper presents the analytical modeling of an energy harvesting system composed of a linear piezoelectric resonator associated to the tunable SECE interface. Contrary to previous model limited to describe the system behavior at resonance, this model enables to extend the analysis off-resonance. The presented theoretical analysis and experimental results clearly show the possibility to increase both the power and the frequency bandwidth by adequate control of the tunable SECE interface.