scholarly journals Enhancing Wind Energy Harvesting Using Passive Turbulence Control Devices

2019 ◽  
Vol 9 (5) ◽  
pp. 998 ◽  
Author(s):  
Junlei Wang ◽  
Guoping Li ◽  
Shengxi Zhou ◽  
Grzegorz Litak
Keyword(s):  
Wind Speed ◽  
Energy Harvesting ◽  
Output Power ◽  
Electromechanical Coupling ◽  
Load Resistance ◽  
Turbulence Control ◽  
Critical Wind Speed ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Passive Turbulence Control

Aiming to predict the performance of galloping piezoelectric energy harvesters, a theoretical model is established and verified by experiments. The relative error between the model and experimental results is 5.3%. In addition, the present model is used to study the AC output characteristics of the piezoelectric energy harvesting system under passive turbulence control (PTC), and the influence of load resistance on the critical wind speed, displacement, and output power under both strong and weak coupling are analyzed from the perspective of electromechanical coupling strength, respectively. The results show that the critical wind speed initially increases and then decreases with increasing load resistance. For weak and critical coupling cases, the output power firstly increases and then decreases with the increase of the load resistance, and reaches the maximum value at the optimal load. For the weak, critical, and strong coupling cases, the critical optimal load is 1.1 MΩ, 1.1 MΩ, and 3.0 MΩ, respectively. Overall, the response mechanism of the presented harvester is revealed.

scholarly journals Analytical Electromechanical Modeling of Nanoscale Flexoelectric Energy Harvesting

2019 ◽  
Vol 9 (11) ◽  
pp. 2273 ◽  
Author(s):  
Yaxuan Su ◽  
Xiaohui Lin ◽  
Rui Huang ◽  
Zhidong Zhou
Keyword(s):  
Energy Harvesting ◽  
Power Density ◽  
Output Power ◽  
Electromechanical Coupling ◽  
Scale Effects ◽  
Dielectric Materials ◽  
Small Scale ◽  
Mechanical Excitation ◽  
Piezoelectric Energy ◽  
Intrinsic Length

With the attention focused on harvesting energy from the ambient environment for nanoscale electronic devices, electromechanical coupling effects in materials have been studied for many potential applications. Flexoelectricity can be observed in all dielectric materials, coupling the strain gradients and polarization, and may lead to strong size-dependent effects at the nanoscale. This paper investigates the flexoelectric energy harvesting under the harmonic mechanical excitation, based on a model similar to the classical Euler–Bernoulli beam theory. The electric Gibbs free energy and the generalized Hamilton’s variational principle for a flexoelectric body are used to derive the coupled governing equations for flexoelectric beams. The closed-form electromechanical expressions are obtained for the steady-state response to the harmonic mechanical excitation in the flexoelectric cantilever beams. The results show that the voltage output, power density, and mechanical vibration response exhibit significant scale effects at the nanoscale. Especially, the output power density for energy harvesting has an optimal value at an intrinsic length scale. This intrinsic length is proportional to the material flexoelectric coefficient. Moreover, it is found that the optimal load resistance for peak power density depends on the beam thickness at the small scale with a critical thickness. Our research indicates that flexoelectric energy harvesting could be a valid alternative to piezoelectric energy harvesting at micro- or nanoscales.

Energy harvesting from a piezoelectric slipper during walking

2017 ◽  
Vol 29 (7) ◽  
pp. 1456-1463 ◽  
Author(s):  
Youngsu Cha ◽  
Jiyeon Seo
Keyword(s):  
Energy Harvesting ◽  
Walking Speed ◽  
Load Resistance ◽  
Power Delivery ◽  
Heel Strike ◽  
Foot Pressure ◽  
Output Measurement ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Energy Transducer

In this article, we study energy harvesting during human walking from a slipper that hosts a piezoelectric energy transducer. Specifically, we demonstrate the feasibility of energy harvesting when a human wearing a slipper without a heel counter walks on a treadmill. In contrast to other work, we focus on the bending of the slipper instead of the heel strike and foot pressure as an energy source. We analyze the deflection and electrical behavior of the slipper through video analysis and voltage output measurement, respectively. We observe the oscillation of the slipper after its toe-off and the effect of high harmonics on the slipper bending. Additionally, we predict the harvested power delivery to load resistances from the piezoelectric slipper using a model and compare it with the experimental results. We find that the harvested power increases and optimal load resistance decreases with walking speed.

Flexoelectric Energy Harvesting of Circular Rings

2013 ◽  
Author(s):  
X. F. Zhang ◽  
S. D. Hu ◽  
H. S. Tzou
Keyword(s):  
Energy Harvesting ◽  
Output Power ◽  
Strain Gradient ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Design Parameters ◽  
Equivalent Resistance ◽  
Flexoelectric Effect ◽  
Piezoelectric Energy

Flexoelectricity, the electromechanical coupling of the polarization response and strain gradient, occurs in solid crystalline dielectrics of any symmetry or asymmetric crystals. Different from the piezoelectric energy harvester, an energy harvester based on the direct flexoelectric effect is designed in this study. The energy harvester consists of an elastic ring and a flexoelectric patch laminated on its outer surface. Due to the direct flexoelectric effect, the electric energy induced by the strain gradient of the flexoelectric patch is harvested to power the electric device when the ring is subjected to mechanical excitations. Electromechanical coupling equation of the flexoelectric energy harvesting system in close-loop circuit condition is derived. In this study, dynamic response, output power across the external resistor and energy harvesting results are evaluated when the ring is excited by a harmonic point loading. The output power is a function of the external excitation frequency, the external equivalent resistance, the flexoelectric patch’s thickness and other design parameters. Case studies of those parameters for the flexoelectric energy harvester are presented to optimize the output power. Results show that the optimal excitation frequency is equal to the natural frequency for each mode, and the optimal equivalent resistance is dependent of the equivalent capacitance of the flexoelectric patch and the excitation frequency. Since the output power of the flexoelectric energy harvester is similar to that of the piezoelectric energy harvester, comparison of the two harvesters is also discussed. With all the optimal conditions discussed, it can supply a design principle in the engineering applications.

scholarly journals Analytical Modeling of a Doubly Clamped Flexible Piezoelectric Energy Harvester with Axial Excitation and Its Experimental Characterization

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3861
Author(s):  
Jie Mei ◽  
Qiong Fan ◽  
Lijie Li ◽  
Dingfang Chen ◽  
Lin Xu ◽  
...  
Keyword(s):  
Output Power ◽  
Power Output ◽  
Output Voltage ◽  
Energy Harvester ◽  
Load Resistance ◽  
Engineering Practice ◽  
Maximum Output ◽  
Widespread Application ◽  
Piezoelectric Energy ◽  
Axial Excitation

With the rapid development of wearable electronics, novel power solutions are required to adapt to flexible surfaces for widespread applications, thus flexible energy harvesters have been extensively studied for their flexibility and stretchability. However, poor power output and insufficient sensitivity to environmental changes limit its widespread application in engineering practice. A doubly clamped flexible piezoelectric energy harvester (FPEH) with axial excitation is therefore proposed for higher power output in a low-frequency vibration environment. Combining the Euler–Bernoulli beam theory and the D’Alembert principle, the differential dynamic equation of the doubly clamped energy harvester is derived, in which the excitation mode of axial load with pre-deformation is considered. A numerical solution of voltage amplitude and average power is obtained using the Rayleigh–Ritz method. Output power of 22.5 μW at 27.1 Hz, with the optimal load resistance being 1 MΩ, is determined by the frequency sweeping analysis. In order to power electronic devices, the converted alternating electric energy should be rectified into direct current energy. By connecting to the MDA2500 standard rectified electric bridge, a rectified DC output voltage across the 1 MΩ load resistor is characterized to be 2.39 V. For further validation of the mechanical-electrical dynamical model of the doubly clamped flexible piezoelectric energy harvester, its output performances, including both its frequency response and resistance load matching performances, are experimentally characterized. From the experimental results, the maximum output power is 1.38 μW, with a load resistance of 5.7 MΩ at 27 Hz, and the rectified DC output voltage reaches 1.84 V, which shows coincidence with simulation results and is proved to be sufficient for powering LED electronics.

scholarly journals An Optimized Flutter-Driven Triboelectric Nanogenerator with a Low Cut-In Wind Speed

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 366
Author(s):  
Yang Xia ◽  
Yun Tian ◽  
Lanbin Zhang ◽  
Zhihao Ma ◽  
Huliang Dai ◽  
...  
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Energy Harvesting ◽  
Wind Energy ◽  
Output Power ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Triboelectric Nanogenerator ◽  
Vibration Behavior ◽  
Air Speed

We present an optimized flutter-driven triboelectric nanogenerator (TENG) for wind energy harvesting. The vibration and power generation characteristics of this TENG are investigated in detail, and a low cut-in wind speed of 3.4 m/s is achieved. It is found that the air speed, the thickness and length of the membrane, and the distance between the electrode plates mainly determine the PTFE membrane’s vibration behavior and the performance of TENG. With the optimized value of the thickness and length of the membrane and the distance of the electrode plates, the peak open-circuit voltage and output power of TENG reach 297 V and 0.46 mW at a wind speed of 10 m/s. The energy generated by TENG can directly light up dozens of LEDs and keep a digital watch running continuously by charging a capacitor of 100 μF at a wind speed of 8 m/s.

scholarly journals Load Resistance Optimization of a Broadband Bistable Piezoelectric Energy Harvester for Primary Harmonic and Subharmonic Behaviors

2021 ◽  
Vol 13 (5) ◽  
pp. 2865 ◽  
Author(s):  
Sungryong Bae ◽  
Pilkee Kim
Keyword(s):  
Energy Harvester ◽  
Load Resistance ◽  
Oscillation Period ◽  
Ambient Vibration ◽  
Ambient Vibrations ◽  
Frequency Dependency ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Bistable Energy Harvester

In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.

Performance analysis of a lever piezoelectric energy harvester for roadway applications

2021 ◽  
pp. 1045389X2110014
Author(s):  
Guangya Ding ◽  
Hongjun Luo ◽  
Jun Wang ◽  
Guohui Yuan
Keyword(s):  
Output Power ◽  
Energy Harvester ◽  
Open Circuit ◽  
Traffic Load ◽  
Energy Harvesters ◽  
Speed Sensor ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Self Powered ◽  
Output Characteristics

A novel lever piezoelectric energy harvester (LPEH) was designed for installation in an actual roadway for energy harvesting. The model incorporates a lever module that amplifies the applied traffic load and transmits it to the piezoelectric ceramic. To observe the piezoelectric growth benefits of the optimized LPEH structure, the output characteristics and durability of two energy harvesters, the LPEH and a piezoelectric energy harvester (PEH) without a lever, were measured and compared by carrying out piezoelectric performance tests and traffic model experiments. Under the same loading condition, the open circuit voltages of the LPEH and PEH were 20.6 and 11.7 V, respectively, which represents a 76% voltage increase for the LPEH compared to the PEH. The output power of the LPEH was 21.51 mW at the optimal load, which was three times higher than that of the PEH (7.45 mW). The output power was linearly dependent on frequency and load, implying the potential application of the module as a self-powered speed sensor. When tested during 300,000 loading cycles, the LPEH still exhibited stable structural performance and durability.

scholarly journals Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Min Zhang ◽  
YingZheng Liu ◽  
ZhaoMin Cao
Keyword(s):  
Energy Harvesting ◽  
Free Stream ◽  
Piezoelectric Materials ◽  
Load Resistance ◽  
Stream Velocity ◽  
Piezoelectric Energy Harvesting ◽  
Vibratory System ◽  
System Parameters ◽  
Piezoelectric Energy ◽  
Vortex Induced Vibrations

A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power.

scholarly journals Modeling and Experiment of a V-Shaped Piezoelectric Energy Harvester

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Yue Zhao ◽  
Yi Qin ◽  
Lei Guo ◽  
Baoping Tang
Keyword(s):  
Energy Harvesting ◽  
Frequency Band ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Structural Parameters ◽  
Ambient Vibration ◽  
Piezoelectric Bimorph ◽  
Actual Structure ◽  
Piezoelectric Energy ◽  
Operation Frequency

Vibration-based energy harvesting technology is the most promising method to solve the problems of self-powered wireless sensor nodes, but most of the vibration-based energy harvesters have a rather narrow operation bandwidth and the operation frequency band is not convenient to adjust when the ambient frequency changes. Since the ambient vibration may be broadband and changeable, a novel V-shaped vibration energy harvester based on the conventional piezoelectric bimorph cantilevered structure is proposed, which successfully improves the energy harvesting efficiency and provides a way to adjust the operation frequency band of the energy harvester conveniently. The electromechanical coupling equations are established by using Euler-Bernoulli equation and piezoelectric equation, and then the coupled circuit equation is derived based on the series connected piezoelectric cantilevers and Kirchhoff's laws. With the above equations, the output performances of V-shaped structure under different structural parameters and load resistances are simulated and discussed. Finally, by changing the angle θ between two piezoelectric bimorph beams and the load resistance, various comprehensive experiments are carried out to test the performance of this V-shaped energy harvester under the same excitation. The experimental results show that the V-shaped energy harvester can not only improve the frequency response characteristic and the output performance of the electrical energy, but also conveniently tune the operation bandwidth; thus it has great application potential in actual structure health monitoring under variable working condition.

Investigation of Power Harvesting via Parametric Excitations

2008 ◽  
Vol 20 (5) ◽  
pp. 545-557 ◽  
Author(s):  
Mohammed F. Daqaq ◽  
Christopher Stabler ◽  
Yousef Qaroush ◽  
Thiago Seuaciuc-Osório
Keyword(s):  
Output Power ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Multiple Scales ◽  
Broad Band ◽  
Parametric Instability ◽  
Load Resistance ◽  
Resistive Load ◽  
Parametrically Excited ◽  
Critical Excitation

This article presents an analytical and experimental investigation of energy harvesting via parametrically excited cantilever beams. To that end, we consider a lumped-parameter non-linear model that describes the first-mode dynamics of a parametrically excited cantilever-type harvester. The model accounts for the beam's geometric and inertia non-linearities as well as non-linearities representing air drag. Using the method of multiple scales, we obtain approximate analytical expressions describing the beam response, voltage drop across a purely resistive load, and output power in the vicinity of the first principle parametric resonance. Using these expressions, we study the effect of the electromechanical coupling and load resistance on the output power. We show that these parameters play an imperative role in determining the magnitude of the output power and characterizing the broad-band properties of the harvester. Specifically, we show that the region of parametric instability wherein energy can be harvested shrinks as the coupling coefficient increases. Furthermore, we show that there exists a coupling coefficient beyond which the peak power decreases. We also demonstrate that there is a critical excitation level below which no energy can be harvested. The amplitude of this critical excitation increases with the coupling coefficient and is maximized for a given load resistance. Theoretical findings that were compared to experimental results show good agreement and reflect the general trends.

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