scholarly journals Modular Environment for Development and Characterization of Tunable Energy Harvesting Systems

2018 ◽  
Vol 21 (2) ◽  
pp. 53
Author(s):  
Javier Casatorres-Aguero ◽  
Octavio Nieto-Taladriz

This paper presents the design and development process for an electromagnetic self-tuned vibrational energy harvester prototype. Most state-of-the-art publications present non-tunable or manually tunable vibrational energy harvesters, even the market provides some commercial models of these categories for specific applications. On the other hand, self-tuned energy harvesters are yet rarely seen on the research community. The presented work follows the complete process of designing a prototype to work as a second-order oscillatory system in the form of a cantilever. Three different approaches to tune the resonant frequency of the harvester were considered, each based in changing a property of the cantilever that modifies its resonant frequency. Firstly, it was changed the effective vibrating length of the cantilever. Secondly it was introduced an axial load to the system. Then, the use of a dual cantilever wishbone structure was studied as it allows changing the equivalent stiffness of the system. Finally a prototype based on the first strategy was built and tested, including control algorithms for the maximum electrical energy harvesting point tracking which are presented.

Author(s):  
Lin Dong ◽  
Frank T. Fisher

Vibration-based energy harvesting has been widely investigated to as a means to generate low levels of electrical energy for applications such as wireless sensor networks. However, due to the fact that vibration from the environment is typically random and varies with different magnitudes and frequencies, it is a challenge to implement frequency matching in order to maximize the power output of the energy harvester with a wider frequency bandwidth for applications where there is a time-dependent, varying source frequency. Possible solutions of frequency matching include widening the bandwidth of the energy harvesters themselves in order to implement frequency matching and to perform resonance-based tuning approach, the latter of which shows the most promise to implement a frequency matching design. Here three tuning strategies are discussed. First a two-dimensional resonant frequency tuning technique for the cantilever-geometry energy harvesting device which extended previous 1D tuning approaches was developed. This 2D approach could be used in applications where space constraints impact the available design space of the energy harvester. In addition, two novel resonant frequency tuning approaches (tuning via mechanical stretch and tuning via applied bias voltage, respectively) for electroactive polymer (EAP) membrane-based geometry energy harvesters was proposed, such that the resulting changes in membrane tension were used to tune the device for applications targeting variable ambient frequency environments.


Author(s):  
Aneesh Koka ◽  
Henry A. Sodano

Piezoelectric nanowires (NWs) have recently attracted immense interest due to their excellent electro-mechanical coupling behavior that can efficiently enable conversion of low-intensity mechanical vibrations for powering or augmenting batteries of biomedical devices and portable consumer electronics. Specifically, nano-electromechanical systems (NEMS) composed of piezoelectric NWs offer an exciting potential for energy harvesting applications due to their enhanced flexibility, light weight, and compact size. Compared to the bulk form, high aspect ratio NWs can exhibit higher deformation to produce an enhanced piezoelectric response at a lower stress level. NEMS made of conventional semiconducting vertically aligned, ZnO NW arrays have been investigated thoroughly for energy harvesting; however, ZnO has a lower piezoelectric coupling coefficient as compared to many ferroelectric ceramics which limits its piezoelectric performance. Amidst lead-free ferroelectric materials, environmentally-friendly barium titanate (BaTiO3) possesses one of the highest piezoelectric strain coefficients and thus can enable greater energy transfer when used in vibrational energy harvesters. In this paper, a novel NEMS energy harvester is fabricated using ultra-long (∼40 μm long), vertically aligned BaTiO3 NW arrays which has a low resonant frequency (below 200 Hz) and its AC power harvesting capacity from low amplitude base vibrations (0.25 g) is demonstrated. The design and fabrication of low resonant frequency vibrational energy harvesters has been challenging in the field of MEMS/NEMS since the high stiffness of the structures results in resonant frequency often greater than 1 kHz. However, ambient mechanical vibrations usually exist in the 1 Hz to 1 kHz range and thus highly complaint ultra-long, NW arrays are beneficial to enable efficient energy conversion. Through the use of this newly developed synthesis process for the growth of highly compliant, ultra-long BaTiO3 NW arrays, it is shown that piezoelectric NWs based NEMS energy harvesters capable of harnessing this low frequency ambient vibrational energy can be conceived.


2019 ◽  
Vol 113 ◽  
pp. 03010 ◽  
Author(s):  
Alessandra Cuneo ◽  
Stefano Barberis ◽  
Alberto Traverso ◽  
Paolo Silvestri

There are several small energy sources that can be exploited to provide useful energy: small temperature differences, mechanical vibrations, flow variations, latent exhausts are just some examples. The recovery of such common and small energy sources, usually wasted, for example with the conversion into useful amounts of electrical energy, is called energy harvesting. Energy harvesting allows low-power embedded devices to be powered from naturally-occurring or unwanted environmental energy (e.g. pressure or temperature difference). The main aim in the last years of researches in such field, was the increasing of the efficiency of such components, with a higher power output and a smaller size. At present, a wide range of systems incorporating energy harvesters are now available commercially, all of them specific to certain types of energy source. Energy harvesting from dissipation processes such as fluid lamination is a challenge for many different applications. In addition, control valves to dissipate overpressures are common usage of many plants and systems. This paper surveys the market opportunities of such harvesting systems, considering the trade-offs affecting their efficiency, their applicability, and ease of deployment. Particular attention will be devoted to small energy harvesters than can exploit small expansions, such as from lamination valves or to systems that can feed mini sensors from small pressure drops, promising compactness, efficiency and cost effectiveness.


Author(s):  
Reza Madankan ◽  
M. Amin Karami ◽  
Puneet Singla

This paper presents the relation between uncertainty in the excitation and parameters of vibrational energy harvesting systems and their power output. Nonlinear vibrational energy harvesters are very sensitive to the frequency of the base excitation. If the excitation frequency does not match with the resonance frequency of the energy harvester, the power output significantly deteriorates. The mismatch can be due to the inherent changes of the ambient oscillations. The fabrication errors or gradual changes of material properties also result in the mismatch. This paper quantitatively shows the probability density function for the power as a function of the probability densities of the excitation frequency, excitation amplitude, initial deflection of the energy harvester, and design parameters. Recently developed the conjugated unscented transformation methodology is used in conjunction with the principle of maximum entropy to compute the probability distribution for the base response and power. The computed nonlinear density functions are validated against Monte Carlo simulations.


Author(s):  
Virgilio J Caetano ◽  
Marcelo A Savi

Energy harvesting from ambient vibration through piezoelectric devices has received a lot of attention in recent years from both academia and industry. One of the main challenges is to develop devices capable of adapting to diverse sources of environmental excitation, being able to efficiently operate over a broadband frequency spectrum. This work proposes a novel multimodal design of a piezoelectric energy harvesting system to harness energy from a wideband ambient vibration source. Circular-shaped and pizza-shaped designs are employed as candidates for the device, comparing their performance with classical beam-shaped devices. Finite element analysis is employed to model system dynamics using ANSYS Workbench. An optimization procedure is applied to the system aiming to seek a configuration that can extract energy from a broader frequency spectrum and maximize its output power. A comparative analysis with conventional energy harvesting systems is performed. Numerical simulations are carried out to investigate the harvester performances under harmonic and random excitations. Results show that the proposed multimodal harvester has potential to harness energy from broadband ambient vibration sources presenting performance advantages in comparison to conventional single-mode energy harvesters.


2012 ◽  
Vol 476-478 ◽  
pp. 1336-1340
Author(s):  
Kai Feng Li ◽  
Rong Liu ◽  
Lin Xiang Wang

The concept of energy harvesting works towards developing self-powered devices that do not require replaceable power supplies. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with ferroelectric materials. Ferroelectric materials have a crystalline structure that provide a unique ability to convert an applied electrical potential into a mechanical strain or vice versa. Based on the properties of the material, this paper investigates the technique of power harvesting and storage.


Author(s):  
Saman Farhangdoust ◽  
Gary Georgeson ◽  
Jeong-Beom Ihn ◽  
Armin Mehrabi

Abstract These days, piezoelectric energy harvesting (PEH) is introduced as one of the clean and renewable energy sources for powering the self-powered sensors utilized for wireless condition monitoring of structures. However, low efficiency is the biggest drawback of the PEHs. This paper introduces an innovative embedded metamaterial subframe (MetaSub) patch as a practical solution to address the low throughput limitation of conventional PEHs whose host structure has already been constructed or installed. To evaluate the performance of the embedded MetaSub patch (EMSP), a cantilever beam is considered as the host structure in this study. The EMSP transfers the auxetic behavior to the piezoelectric element (PZT) wherever substituting a regular beam with an auxetic beam is either impracticable or suboptimal. The concept of the EMSP is numerically validated, and the COMSOL Multiphysics software was employed to investigate its performance when a cantilever beam is subjected to different amplitude and frequency. The FEM results demonstrate that the harvesting power in cases that use the EMSP can be amplified up to 5.5 times compared to a piezoelectric cantilever energy harvester without patch. This paper opens up a great potential of using EMSP for different types of energy harvesting systems in biomedical, acoustics, civil, electrical, aerospace, and mechanical engineering applications.


This Paper presents a new technique of electrical energy generation using mechanically excited piezoelectric materials and a nonlinear process. This technique, called double synchronized switch harvesting (DSSH), is derived from the synchronized switch damping (SSD), which is a nonlinear technique previously developed to address the problem of vibration damping on mechanical structures. This technique results in a significant increase of the electromechanical conversion capability of piezoelectric materials. An optimized method of harvesting vibrational energy with a piezoelectric element using a dc–dc converter is presented. In this configuration, the converter regulates the power flow from the piezoelectric element to the desired electronic load. Analysis of the converter in discontinuous current conduction mode results in an expression for the duty cycle-power relationship. Using parameters of the mechanical system, the piezoelectric element, and the converter; the “optimal” duty cycle can be determined where the harvested power is maximized for the level of mechanical excitation. A circuit is proposed which implements this relationship, and experimental results show that the converter increases the harvested power by approximately 365% as compared to when the dc–dc converter is not used


2019 ◽  
Author(s):  
Mohammadsadegh Saadatzi ◽  
Mohammad Nasser Saadatzi ◽  
Sourav Banerjee

Abstract In the current study, a novel multi-frequency, vibration-based Energy Harvester (EH) is proposed, numerically verified, and experimentally validated. The structural design of the proposed EH is inspired from an inner-ear, snail-shaped structure. In the past decade, scavenging power from environmental sources of vibration has attracted a lot of researchers to the field of energy harvesting. High demands for cleaner and renewable energy sources, limited sources of electrical energy, high depletion rates of nonrenewable sources of energy, and environmental concerns have urged researchers to investigate new structures called Metamaterial energy harvesters to harness electrical potential. The proposed EH is a metamaterial structure which has a Polyvinylidene Difluoride (PVDF) structure incapsulated in an aluminum frame and follows the physics of a mass-in-mass Phononic crystal structure. The PVDF snail-shaped structure is encapsulated inside a silicone matrix with a specific material property. This EH reacts to the environmental vibrations and the encapsulating silicone entraps the kinetic energy within its structure. The EH unit cell behaves as a negative mass in the vicinity of its resonance frequencies. In this paper, the dynamic behavior of the proposed EH is numerically modeled in COMSOL Multiphysics and, subsequently, validated experimentally using a unit cell fabricated in-house.


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