Bandwidth Widening of Piezoelectric Cantilever Beam Arrays by Mass-Tip Tuning for Low-Frequency Vibration Energy Harvesting

Abstract

Featured Application: The results of the present work can be used to develop vibration energy harvesters supplying wireless sensor nodes. This is feasible since the order of magnitude of harvested electrical power is 1 mW.Abstract: Wireless sensor networks usually rely on internal permanent or rechargeable batteries as a power supply, causing high maintenance efforts. An alternative solution is to supply the entire system by harvesting the ambient energy, for example, by transducing ambient vibrations into electric energy by virtue of the piezoelectric effect. The purpose of this paper is to present a simple engineering approach for the bandwidth optimization of vibration energy harvesting systems comprising multiple piezoelectric cantilevers (PECs). The frequency tuning of a particular cantilever is achieved by changing the tip mass. It is shown that the bandwidth enhancement by mass tuning is limited and requires several PECs with close resonance frequencies. At a fixed frequency detuning between subsequent PECs, the achievable bandwidth shows a saturation behavior as a function of the number of cantilevers used. Since the resonance frequency of each PEC is different, the output voltages at a particular excitation frequency have different amplitudes and phases. A simple power-transfer circuit where several PECs with an individual full wave bridge rectifier are connected in parallel allows one to extract the electrical power close to the theoretical maximum excluding the diode losses. The experiments performed on two-and three-PEC arrays show reasonable agreement with simulations and demonstrate that this power-transfer circuit additionally influences the frequency dependence of the harvested electrical power.

Analysis and Experimental Validation of a Piezoelectric Harvester with Enhanced Frequency Bandwidth

“…Moreover, the three bimorphs system has a larger output power, and by adding an additional bimorph (the middle one), the width of the “power pit” is reduced. Similar results were published in [26,37]. …”

“…A preferred end mass ratio should be 10–20, depending on system geometry and spring rate. The same conclusion can be found in [26,37]. Note that a complete disappearance of the power pit can be achieved only for the case of two very close natural frequencies, yielding a narrow bandwidth, and therefore not applicable.…”

“…After validating their models using the COMSOL code, they found that a significant broadband (about 10 Hz) can be observed for the parallel connection of the oscillators having the parallel-SSHI circuit, yielding approximately 60 μW, or a bandwidth of 10 Hz with a peak power of 60 μW for series connection of the oscillators having serial SSHI circuit. A recent paper by Dechant et al [37] continued the trend presented above, trying to enhance the bandwidth of vibration energy harvester system by using three piezoelectric cantilevers having tip masses to achieve a frequency tuning for each cantilever. They found that the bandwidth enhancement by mass tuning is limited and requires several bimorphs with close resonance frequencies.…”

Vibration Energy Harvest for Low Frequency using Double- piezoelectric Cantilever Beam

“…Several papers [2][3][4][5] present the multiple cantilever beam arrays. It increases bandwidth and electric power for scavenge vibration energy ambient.…”

Hysteresis characteristics influence on the super-harmonic vibration of a bi-stable piezoelectric energy harvester

“…1 It is indicated that the nonlinear behavior can not only offer new capabilities to capture energy available from more complex excitations but also have the advantage of broadening the frequency range of vibrations energy harvesting. 2,3 By the super-harmonic vibration behavior, a nonlinear resonator is designed and fabricated for ultra-wide-bandwidth energy harvesting applications, 4 the nonlinear resonances can activate large-amplitude motions at fraction integers of the fundamental frequency of the system, 5 a mathematic model for the nonlinear energy harvester may be simplified as the form of a Duffing oscillator 6 and a new method for the dynamical features of stochastic nonlinear oscillators is proposed, 7 and the performances of nonlinear energy harvesters are researched by exploiting benefits of a periodically forced double-well oscillator. 8 However, it has been thought that the smart structures have other nonlinearity, for example, hysteresis phenomenon.…”