Resonant inverter design for stand-alone dynamic active piezoelectric energy harvesting

Piezoelectric energy harvesters generate electrical power from ambient mechanical vibrations, making these vibrations a viable energy source for powering wireless sensor and identifier nodes. In order to harvest an appreciable amount of power, piezoelectric devices are typically inserted into high-Q mechanical resonant structures that significantly limit their harvesting bandwidth. Recently, active dynamic energy harvesting techniques have been proposed as a way to widen the bandwidth of resonant piezoelectric energy harvesters; however, a practical stand-alone design has not yet been demonstrated. This paper describes a new resonant inverter topology that implements the dynamic active energy harvesting technique. Experimental results using the Mide Volture V20w piezoelectric device show that over the applied frequency band, this system harvests up to 7.7 times more power at off-resonant frequencies and twice as much power near the resonant frequency when compared to an adaptive rectifier circuit. These results occur while including previously ignored loss mechanisms such as control losses, gating losses, and phase detection losses, and demonstrate the feasibility of a stand-alone system.