High performance piezoelectric vibration energy harvesting by electrical resonant frequency tuning

Abstract

Extending the frequency bandwidth of vibration energy harvesters (VEH) that power wireless sensor nodes is of scientific and industrial interest. In this aim, electrical methods to tune the resonant frequency of piezoelectric harvesters with strong electromechanical coupling coefficients have been developed. In this work, we provide guidelines for designing such strongly coupled VEH and present a broadband harvester with high normalized power density (NPD). Through an analytical model, we explain how the coupling coefficient k² and the quality factor Qm of a cantilever can be jointly maximized, thereby maximizing the figure of merit ke²Qm. The proposed cantilever prototype made of PZN-5.5PT and aluminum offers one of the best coupling coefficients among the state-of-the-art (k²=49.8%) and a high quality factor (Qm=140). Associated to an appropriate tunable electrical interface (short-circuit synchronous electric charge extraction in our case), the prototype exhibits a normalized power density of 12.0 mW/g²/cm3 and a frequency bandwidth (BW) of 36.0 % (56.5 Hz around 157 Hz) at 0.34 m/s² with a tunable electrical interface: the short-circuit synchronous electric charge extraction. This represents the highest product NPW×BW from state of the art.

Are piezoelectric-electromagnetic hybrid energy harvesting systems beneficial?

“…There are various possible pathways to increase the effective figures of merit M E and M P , for example, reducing the mechanical damping, designing (and operating) a system with a higher resonance frequency at a given coupling coefficient, or minimizing the electrically parasitic losses. The first method depends on packaging technologies, such as fabricating a device in a vacuum or creating a rigid anchor to prevent thermal losses at clamping points [27,30]. Meanwhile, the harvester resonance frequency is usually designed depending on the frequency of the environmental vibration.…”

Stabilization against gravity and self-tuning of an elastic variable-length rod through an oscillating sliding sleeve

“…The presented results introduce a new paradigm in nonlinear structural dynamics and may find applications for positioning tasks in soft robotics [1,18,19], as well as for wave mitigation devices [10,13,15,20] and environmental energy harvesters [7,14,22], where self-tuning property can be exploited to improve efficiency and to extend the frequency range of application.…”

A frequency up-conversion rotational energy harvester with auxetic structures for high power output

“…There are four commonly used mechanisms to transform mechanical energy into electrical power including electrostatic [6], electromagnetic [7], piezoelectric [8][9][10], and triboelectric [11,12] mechanisms. Among them, the piezoelectric one is widely adopted for its ease of integrability and high power density [13][14][15]. The traditional small-scale cantilevered energy harvester can produce the maximum power near the high resonant frequency.…”