Behavior Of Energy Harvester Research Articles

Nonlinear Analysis and Closed-Form Solution for Overhead Line Magnetic Energy Harvester Behavior

Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core’s BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found.

Energy-harvesting behavior and configuration effect of two semi-active flapping foils

Energy-harvesting behavior and configuration effect of two semi-active flapping foils

A model-based approach for formal verification and performance evaluation of energy harvesting architectures in IoT systems: A case study of a long-term healthcare application

Energy harvesting plays a significant role in the Internet of Things (IoT). Indeed, although numerous approaches exist to limit the system’s power consumption, the energy provided by the battery remains constrained, thereby limiting the system’s lifetime. Energy harvesting represents an interesting technique that allows a set of devices in an IoT architecture to operate for a potentially infinite time without the need for battery replacement or recharge. This work presents a formal modeling framework for the performance evaluation of energy harvesting architectures and strategies in IoT systems. We present a model-based approach using UPPAAL to model and analyze IoT device lifetimes and capture the energy-related behavior of nodes and various energy harvesters. Furthermore, the model is calibrated using measurements acquired from real-life IoT applications to demonstrate the effectiveness of the proposed model and its ability to investigate various energy-related aspects.

Charge generation by passive plant leaf motion at low wind speeds: design and collective behavior of plant-hybrid energy harvesters

Energy harvesting techniques can exploit even subtle passive motion like that of plant leaves in wind as a consequence of contact electrification of the leaf surface. The effect is strongly enhanced by artificial materials installed as ‘artificial leaves’ on the natural leaves creating a recurring mechanical contact and separation. However, this requires a controlled mechanical interaction between the biological and the artificial component during the complex wind motion. Here, we build and test four artificial leaf designs with varying flexibility and degrees of freedom across the blade operating on Nerium oleander plants. We evaluate the apparent contact area (up to 10 cm2 per leaf), the leaves’ motion, together with the generated voltage, current and charge in low wind speeds of up to 3.3 m s−1 and less. Single artificial leaves produced over 75 V and 1 µA current peaks. Softer artificial leaves increase the contact area accessible for energy conversion, but a balance between softer and stiffer elements in the artificial blade is optimal to increase the frequency of contact-separation motion (here up to 10 Hz) for energy conversion also below 3.3 m s−1. Moreover, we tested how multiple leaves operating collectively during continuous wind energy harvesting over several days achieve a root mean square power of ∼6 µW and are capable to transfer ∼80 µC every 30–40 min to power a wireless temperature and humidity sensor autonomously and recurrently. The results experimentally reveal design strategies for energy harvesters providing autonomous micro power sources in plant ecosystems for example for sensing in precision agriculture and remote environmental monitoring.

Improvement of the Non-periodic Energy Harvesting Behavior of a Non-ideal Magnetic Levitation System Utilizing Internal Resonance

Improvement of the Non-periodic Energy Harvesting Behavior of a Non-ideal Magnetic Levitation System Utilizing Internal Resonance

Energy harvesting and dynamic response of SMA nano conical panels with nanocomposite piezoelectric patch under moving load

Nowadays, the application of advanced and intelligent materials such as piezoelectric, shape memory alloys (SMA), and multi-phase materials, are highly demanded, especially in self-powered energy structures. Therefore, to obtain maximum efficiency, it is crucial to study and analysis the mechanical behavior of the energy production rate of the employed materials. This research theoretically evaluated the impacts of moving load and the use of a piezoelectric patch on the level of energy harvesting and dynamic behavior of a Nano Conical Panel (NCP) made from SMA located on a frictional substrate using the First-order Shear Deformation Theory (FSDT). Based on mixture rule, boron nitride nanotubes (BNNTs) with smart properties are used to reinforce the piezoelectric patch. A two-phase nonlocal method was adopted to take nano-scale effects into account. Mechanical behaviors such as friction and torsional viscoelastic were considered for the foundation layer. To reproduce the pseudo-elastic characteristics of SMA, the Hernandez-Lagoudas model was employed. In addition to these, Integral Quadrature (IQ), Differential Quadrature (DQ), and Newmark methods were coupled together to solve the equations regarding the output voltage, electric power and dynamic deflection. The computational outcomes showed that by applying a positive voltage to a piezoelectric patch, the maximum strain, as well as the energy harvesting capacity of NCP, were increased. Placing the NCP on a frictional viscoelastic-torsional layer led to deteriorated peak values of dimensionless dynamic displacement and dimensionless voltage by about 50.3% and 44.5%, respectively, compared with those of the system without the medium. At load resistance of 400 nano ohm, increasing the moving load velocity to 6.5 nm/ns, piezoelectric patch length to NCP length ratio up to 0.5, and applying CFCF boundary conditions led to enhancement of maximum output power by 30%, 88.3%, and 377%, respectively. Also, increasing the weight fraction of Boron Nitride Nanotubes (BNNT) up to 0.4% in the piezoelectric layer was found to be a suitable strategy to simultaneously decrease the dimensionless dynamic displacement and enhance dimensionless voltage by 23.4% and 21%, respectively.

Parametric excitation analysis for system performance of piezoelectric energy harvesters

Capitalizing on the advantages of parametric excitation and real-life low frequency vibration, the steady-state response of piezoelectric energy harvesting system composing of a cantilever beam with a tip mass and horizontal excitation at the fixed end is investigated. By applying Hamilton's principle, the nonlinear partial differential equation of a cantilever bimorph piezoelectric energy harvesting system with an additional tip mass is derived and analyzed. The cantilever is modeled as an axially non-elongated Euler Bernoulli beam with geometric and damping nonlinearities. By using the Galerkin method, the nonlinear partial differential equation is reduced to an electromechanical coupling system that governs a cantilever piezoelectric energy harvesting system with a tip mass under parametric excitation. The first-order resonance response of this harvesting system is studied by using the method of multiple scales. The analytical response expressions and first-order amplitude functions for vertical displacement, output voltage and output power are derived and analyzed. The influence of different impedance and tip mass on the piezoelectric energy harvesting system performance is summarized and concluded. For the parametric excitation system, the load resistance shows significant influence on the initial threshold of the piezoelectric energy harvesters under parametric excitation. For a short circuit, the initial threshold increases with increasing load resistance. For an open circuit, the initial threshold decreases with increasing load resistance. For an open circuit resistance or a short circuit resistance under parametric excitation, an increase in the end block mass effectively reduces the resonance frequency of the piezoelectric energy harvesters. Consequently, the energy harvesting bandwidth is increased, and the harvesting effect of the piezoelectric energy harvesters is enhanced. In this paper, a more accurate and practical theoretical model is established to predict the electromechanical coupling behavior of cantilever piezoelectric energy harvester under parametric excitation. Using this approach, it is possible to complement parametric and direct excitation such that the advantages of parametric excitation can be achieved. It is also significant to improve the energy conversion efficiency of energy harvesting system.

Design of multi-step zig-zag shaped piezoelectric energy harvesters for powering fetal heart rate monitoring system

The non-linear behavior of a broadband piezoelectric energy harvester with various configurations (single-layer, multi-layer and multi-step) in multimode operation is designed for powering fetal-heart rate monitoring medical device. In this research work the harvester has a zig-zag uniform structure with a dual-hold composition and three proof masses that improves the harvester’s operational bandwidth. The goal of this study is to find the maximum power generated from the harvester with lowest frequency and large bandwidth for enhancing the effectiveness of the device. The Multi-step energy harvester has proved to be more effective in comparison to single-layer and multi-layer harvesters, respectively.

Negative Poisson’s ratio polyethylene matrix and 0.5Ba(Zr0.2 Ti0.8) O3–0.5(Ba0.7 Ca0.3)TiO3 based piezocomposite for sensing and energy harvesting applications

Finite element studies were conducted on 0.5Ba(Zr0.2 Ti0.8) O3–0.5(Ba0.7 Ca0.3)TiO3 (BCZT) piezoelectric particles embedded in polyethylene matrix to create a piezocomposite having a positive and negative Poisson's ratio of −0.32 and 0.2. Polyethylene with a positive Poisson's ratio is referred to as non-auxetic while those with negative Poisson's ratio are referred to as auxetic or inherently auxetic. The effective elastic and piezoelectric properties were calculated at volume fractions of (4%, 8% to 24%) to study their sensing and harvesting performance. This study compared lead-free auxetic 0–3 piezocomposite for sensing and energy harvesting with non-auxetic one. Inherently auxetic piezocomposites have been studied for their elastic and piezoelectric properties and improved mechanical coupling, but their sensing and energy harvesting capabilities and behavior patterns have not been explored in previous literatures. The effect of Poisson's ratio ranging between −0.9 to 0.4 on the sensing and energy harvesting performance of an inherently auxetic lead free piezocomposite composite with BCZT inclusions has also not been studied before, motivating the author to conduct the present study. Auxetic piezocomposite demonstrated an overall improvement in performance in terms of higher sensing voltage and harvested power. The study was repeated at a constant volume fraction of 24% for a range of Poisson's ratio varied between −0.9 to 0.4. Enhanced performance was observed at the extreme negative end of the Poisson's ratio spectrum. This paper demonstrates the potential improvements by exploiting auxetic matrices in future piezocomposite sensors and energy harvesters.

Distinct stage-wise environmental energy harvesting behaviors within solar-driven interfacial water evaporation coupled with convective airflow

Coupling solar-driven interfacial water evaporation with convective airflow (SIWEC) can lead to significantly improved water evaporation performance due to the enhanced environmental energy harvesting. However, the accurate environmental energy harvesting behaviors in such systems have not been thoroughly explored, leading to often vastly different evaporation performances in the literatures un-reconciled. Here, we present a general experimental and computational framework which allows for a fine investigation on the environmental energy harvesting behaviors of SIWEC, for the first time, delineates three distinct stages of environmental energy harvesting behaviors within SIWEC, and further reveals that the amount of harvestable environmental energy within SIWEC has a moderate maximum. The results of this work highlight the critical size-performance relationship of SIWEC, reconcile many seemingly contradicting performances in the literatures, and help set up a reasonable expectation on the environmental energy harvesting by similar systems in practical applications.

Generalized Analysis Method for Magnetic Energy Harvesters

Large-scale deployment of low-power sensing and computing units calls for unique power management solutions to overcome the inconvenience, costs, and waste problems associated with batteries. Energy harvesting offers an exciting solution to the battery problem, enabling circuits that can power themselves on-site from available ambient energy. Magnetic energy harvesters (MEHs), configured as current transformers, extract energy from the magnetic fields surrounding current-carrying power lines. As maximum power harvest occurs when a magnetic core is on the verge of saturation or saturated to some degree, modeling of magnetic energy harvesters is inherently difficult and nonlinear. This article proposes generalized analytical methods for modeling magnetic energy harvester behavior and validates these methods along with existing circuit model techniques. Intuition for core saturation behavior is presented and agreement with existing models is discussed. The analysis is motivated by addressing the feasibility of a split core magnetic energy harvester to power a microcontroller unit, and the models are experimentally validated for multiple harvester cores.

Agglomeration effects of CNTs on the energy harvesting performance of multifield interactive magneto-electro-elastic/nanocomposite unimorph smart beam

In this article, the effect of agglomeration of carbon nanotubes (CNTs) on the energy harvesting behavior of a unimorph multifunctional cantilever beam (UMCB) subjected to transverse and rotational vibrations is investigated analytically using a distributed parameter model. The top layer of the UMCB consists of the magneto-electro-elastic (MEE) material, formed by reinforcing a piezoelectric matrix with CNTs, acting as a piezomagnetic phase. The substructure of the UMCB is composed of a nanocomposite CNTs material. To address the issue of dispersion of the material, agglomeration or cluster formation of the CNTs in the substrate layer is considered. The agglomeration is modeled using the modified Eshelby-Mori-Tanaka (EMT) method. The ideal case of no agglomeration, partial and complete agglomeration, is considered for evaluation. The various distributions of the CNTs in the substrate and its volume fractions are also considered in the analysis. The coupled governing equations of motion and the subsequent frequency-response functions (FRFs) for the output parameters are derived based on the distributed parameter approach, in conjunction with the Euler-Bernoulli beam theory, Gauss and Faraday’s laws. Various material and geometrical parametric studies are discussed in detail to understand the output response of the UMCB. Special focus is placed on the effect of the agglomerated CNTs substrate and the influence of various agglomeration parameters on the overall output response. The article is a stepping stone to developing and utilizing advanced composite structure-based energy harvesting devices and paves the way for further research into utilizing CNTs-based composite structures for various engineering applications.

Electrical Properties of Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub>/ PVDF(25/75) Composite

The mechanical impact-based energy harvesting behavior of a 0-3 Bi0.5Na0.5TiO3/PVDF(25/75) composite prepared using the melt-mixing method have been demonstrated. X-ray diffraction analyses revealed the formation of a composite sample, while AFM image analyses revealed that BNT-particle sizes ranged between 0.6 and 1.4 μm and were evenly distributed throughout the polymer matrix, and surface roughness was found to be between 0.2 and 1.8 μm. With increasing impact height (applied mechanical energy), a remarkable increase in generated electric voltage and energy was observed. As a result, the present composite is a better lead-free alternative for piezo-sensing/detection and energy harvesting applications.

An electro-mechanical dynamic model for flexoelectric energy harvesters

Flexoelectricity is a universal electro-mechanical coupling effect that occurs in dielectrics of all symmetric groups and becomes dominant at the micro- and nano-scales. It plays an important role in evaluating micro-electro-mechanical systems (MEMS) such as energy harvesters which convert vibrational energy to electric energy. At finer length scales, micro-inertia effects significantly contribute to the behavior of flexoelectric materials due to the mechanical dispersion. Hence, to properly characterize the vibrational behavior of MEMS, a reliable theoretical approach is required accounting for all possible phenomena that affect the output of the system such as voltage or power density. In this work, we present a consistent (dynamic) model and associated computational framework for flexoelectric structures to study the characteristics of the vibrational behavior of energy harvesters showing the dominance of the flexoelectric effect at micro- and nano-scales. In this context, we quantify the impact of the micro-inertia length scale and the flexoelectric dynamic parameter on both frequency and time responses of energy harvesters.

Size-dependent behavior of micro piezoelectric VIV energy harvester: Parametric study and performance analysis

Implementation of self-powered MEMS units by converting wind and flow stream energy into electrical energy has gained substantial interest in recent years. A bluff body vortex induced vibrations (VIV) in combination with micro scale piezoelectric device can be designed to harvest the demanded power. In the present study, the mechanical performance of a piezoelectric micro energy harvester beam attached to a tip cylinder is numerically simulated. In order to increase the accuracy of the modeling, the elastic and piezoelectric micro-beam governing equations are derived based on strain gradient theory instead of the conventionally used classical theory. The actuating aerodynamic lift force due to the vortex shedding downstream of the cylinder, is simulated by the modified van der Pol wake oscillator equation. Using the mode summation and Galerkin method, the three coupled time dependent governing equations are solved. The accuracy of the van der Pol equation is examined by a moving object computational fluid dynamics (CFD) simulation on the basis of the cantilever beam tip deflection and great agreement is achieved. The effect of length scale parameter, beam length, cylinder diameter and mass, load resistance, piezoelectric thickness as well as the fluid velocity on the produced power density is studied. Findings revealed that increasing the length scale parameters, the device stiffness and frequency increases as well as the harvested power is increased at specific fluid velocities. In other words, increasing the length scale from 0 to 2μm, increases the power density up to 77%.

Power characteristics of vibration-based piezoelectric energy harvesters: the effect of piezoelectric material nonlinearity

Piezoelectric energy harvesting has received tremendous interests in the past two decades as a viable solution to self-powered electronics and devices. Recently, significant emphasis has been given to nonlinear energy harvesters driven by the desire for broadband, high-performance energy harvesting. Numerous efforts have been devoted to the understanding and modeling of the electromechanical coupling and the effect of nonlinearities introduced by mechanical and electrical aspects of the system. However, very few works in the literature considered the effect of piezoelectric material nonlinearity on the system power performance. Nevertheless, it has been found that piezoelectric nonlinearity is significant even at low to moderate excitation level. This paper is motivated to study the power behavior of piezoelectric energy harvesters with piezoelectric nonlinearity, most importantly, the power limit and electromechanical coupling. For this purpose, an approximate model is developed from the nonlinear model in the literature to derive the closed-form expressions of important power characteristics. Analytical analysis shows that the effect of piezoelectric material nonlinearity results in a nonlinear damping term and a nonlinear stiffness term in the approximate model. The approximate solutions of optimal load resistance, maximum power, power limit, and critical electromechanical coupling are obtained and validated by numerical simulations first. The induced nonlinear damping reduces the power limit of the system compared to its linear counterpart. Interestingly, a harvester that exhibits strong electromechanical coupling under small excitation could become weakly coupled under large excitation. The analytical analysis and numerical results are validated by experiments.

The optimal design of a piezoelectric energy harvester for smart pavements

The traffic environment contains tremendous mechanical energy due to the dynamic loads of moving vehicles which can be converted into electricity by using piezoelectric materials. Considering the road environmental characteristics, we propose here a piezoelectric energy harvester (PEH) consisting of piezoelectric ceramics that are encapsulated in epoxy resin filler between the MC nylon protective plates. As an illustration, periodic traffic loading is considered and is simulated by a controlled MTS loading, using which the effects of various system parameters on the efficiency of energy harvesting are examined. A theoretical electromechanical model is also developed to predict the energy harvesting behavior of the PEH device. The theoretical predictions agree very well with the experimental measurements, and they both suggest that various load, material, and circuit factors will have diverse effects on output power. To figure out the best collection of all factors and their simultaneous effect on the output performance, we also establish a simple and universal scaling law to reveal the underlying mechanism of the correlation between various systematic parameters. The normalized output power depends only on the normalized intrinsic impedance that consists of all material properties, geometrical, electrical circuit, and loading condition parameters. The optimization strategy may provide a useful tool to guide the design of the PEH device for enhancing the efficiency of energy harvesting by properly selecting the system parameters.

An Investigation on Energy Harvesting Behavior of an Array Piezoelectric Coupled Disc Damper.

In order to make full use of the vibration energy in the process of attenuating vibration, an array piezoelectric coupled disc damper is developed, which works by converting part vibration energy into electrical energy. The piezoelectric damper is made of a pair of piezoelectric coupled discs built in a case cylinder. Its energy harvesting behavior is studied by a series of forced-vibration experiments and simulations. The influences of some factors, such as the excitation frequency, substrate thickness, the size of the piezoelectric patch, the paste form of the piezoelectric patch and the load resistance, on the energy harvesting behavior of the damper are analyzed and concluded. The experimental results show that the maximum peak-to-peak voltage and average power from one piezoelectric patch with an inner diameter of 35 mm, an outer diameter of 80 mm, and a thickness of 1 mm can reach up to 163 V and 161 mW, respectively. This research provides a practical piezoelectric damper attenuating harmful vibration by converting them into useful electric power, and the corresponding theoretical models are derived to predict its electrical output.

Global sensitivity analysis of asymmetric energy harvesters

Parametric variability is inevitable in actual energy harvesters. It can significantly affect crucial aspects of the system performance, especially in harvesting systems that present geometric parameters, material properties, or excitation conditions that are susceptible to small perturbations. This work aims to develop an investigation to identify the most critical parameters in the dynamic behavior of asymmetric bistable energy harvesters with nonlinear piezoelectric coupling, considering the variability of their physical and excitation properties. For this purpose, a global sensitivity analysis based on orthogonal variance decomposition, employing Sobol indices, is performed to quantify the effect of the harvester parameters on the variance of the recovered power. This technique quantifies the variance concerning each parameter individually and collectively regarding the total variation of the model. The results indicate that the frequency and amplitude of excitation, asymmetric terms and electrical proprieties of the piezoelectric coupling are the most critical parameters that affect the mean power harvested. It is also shown that the order of importance of the parameters can change according to the stability of the harvester’s dynamic response. In this way, a better understanding of the system under analysis is obtained since the study allows the identification of vital parameters that rule the change of dynamic behavior and therefore constitutes a powerful tool in the robust design, optimization, and response prediction of nonlinear harvesters.

Investigation on the interphase effects on the energy harvesting characteristics of three phase magneto-electro-elastic cantilever beam

In this work the influence of the interphase region in a three-phase magneto-electro-elastic composite material on the energy harvesting characteristics of a vibration based cantilever beam is studied analytically. The three-phase composite made of Barium Titanate/Terfenol-D/Cobalt Ferrite with different interphase regions have been considered for the evaluation. The mathematical expressions for the coupled governing equations are derived through a lumped parameter model in conjunction with Gauss's Law, Newton's Law and Faraday's Law. The generated electric and magnetic potential are harvested through the surface electrodes and a wound coil. The numerical results suggest that the interphase volume fraction and composition adversely affect the coupled material properties, which in turn significantly alters the output response of the energy harvester. Also, the lower values of resistance and number of turns of coil have a predominant effect on the energy harvester's performance. The results of this work demonstrate the significance of the interphase region and its effects on the coupled energy harvesting behavior in multifunctional composite materials.