scholarly journals A Magnetically Coupled Electromagnetic Energy Harvester with Low Operating Frequency for Human Body Kinetic Energy

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1300
Author(s):  
Xiang Li ◽  
Jinpeng Meng ◽  
Chongqiu Yang ◽  
Huirong Zhang ◽  
Leian Zhang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Human Body ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Excitation Frequency ◽  
Magnetic Coupling ◽  
Interaction Force ◽  
Harmonic Excitation ◽  
Electromagnetic Energy ◽  
Maximum Output

In this paper, a magnetically coupled electromagnetic energy harvester (MCEEH) is proposed for harvesting human body kinetic energy. The proposed MCEEH mainly consists of a pair of spring-connected magnets, coils, and a free-moving magnet. Specifically, the interaction force between the magnets is repulsive. The main feature of this structure is the use of a magnetic-spring structure to weaken the hardening response caused by the repulsive force. The magnetic coupling method enables the energy harvester system to harvest energy efficiently at low frequency. The MCEEH is experimentally investigated for improving energy harvesting efficiency. Under harmonic excitation with an acceleration of 0.5 g, the MCEEH reaches resonance frequency at 8.8 Hz and the maximum output power of the three coils are 5.2 mW, 2.8 mW, and 2.5 mW, respectively. In the case of hand-shaking excitation, the generator can obtain the maximum voltage of 0.6 V under the excitation acceleration of 0.2 g and the excitation frequency of 3.4 Hz. Additionally, a maximum instantaneous power can be obtained of about 26 mW from the human body’s kinetic energy

scholarly journals Study of the Properties of a Hybrid Piezoelectric and Electromagnetic Energy Harvester for a Civil Engineering Low-Frequency Sloshing Environment

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 391
Author(s):  
Nan Wu ◽  
Yuncheng He ◽  
Jiyang Fu ◽  
Peng Liao
Keyword(s):  
Output Power ◽  
Energy Harvester ◽  
Civil Engineering ◽  
Maximum Output Power ◽  
Low Frequency ◽  
Electromagnetic Energy ◽  
Maximum Output ◽  
Piezoelectric Film ◽  
Hybrid Energy ◽  
Level Height

In this paper a novel hybrid piezoelectric and electromagnetic energy harvester for civil engineering low-frequency sloshing environment is reported. The architecture, fabrication and characterization of the harvester are discussed. The hybrid energy harvester is composed of a permanent magnet, copper coil, and PVDF(polyvinylidene difluoride) piezoelectric film, and the upper U-tube device containing a cylindrical fluid barrier is connected to the foundation support plate by a hinge and spring. The two primary means of energy collection were through the vortex street, which alternately impacted the PVDF piezoelectric film through fluid shedding, and the electromotive force (EMF) induced by changes in the magnetic field position in the conducting coil. Experimentally, the maximum output power of the piezoelectric transformer of the hybrid energy harvester was 2.47 μW (circuit load 270 kΩ; liquid level height 80 mm); and the maximum output power of the electromagnetic generator was 2.72 μW (circuit load 470 kΩ; liquid level height 60 mm). The low-frequency sloshing energy collected by this energy harvester can drive microsensors for civil engineering monitoring.

scholarly journals Topology Selection and Parametric Design of Electromagnetic Vibration Energy Harvesters by Combining FEA-in-the-Loop and Analytical Approaches

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 627 ◽  
Author(s):  
Seong-yeol Yoo ◽  
Young-Woo Park ◽  
Myounggyu Noh
Keyword(s):  
Output Power ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Electromagnetic Energy ◽  
Vibration Energy ◽  
Maximum Output ◽  
Primary Concern ◽  
Energy Harvesters ◽  
Analytical Approaches

Electromagnetic energy harvesters have been used to capture low-frequency vibration energy of large machines such as diesel generators. The structure of an electromagnetic energy harvester is either planar or tubular. Past research efforts focus on optimally designing each structure separately. An objective comparison between the two structures is necessary in order to decide which structure is advantageous. When comparing the structures, the design variations such as magnetization patterns and the use of yokes must also be considered. In this study, extensive comparisons are made covering all possible topologies of an electromagnetic energy harvester. A bench mark harvester is defined and the parameters that produce maximum output power are identified for each topology. It is found that the tubular harvesters generally produce larger output power than the planar counterparts. The largest output power is generated by the tubular harvester with a Halbach magnetization pattern (94.7 mW). The second best is the tubular harvester with axial magnetization pattern (79.1 mW) when moving yokes are inserted between permanent magnets for flux concentration. When cost is of primary concern, the tubular harvester with axial pattern may become a best option.

System Parameter Optimization for a Frequency-Up-Conversion Piezoelectric Energy Harvester With Backward Mechanical-Electric Coupling Effect

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Fengxia Wang
Keyword(s):  
Output Power ◽  
Energy Harvester ◽  
Coupling Effect ◽  
Maximum Output Power ◽  
Harmonic Excitation ◽  
Maximum Output ◽  
Piezoelectric Energy ◽  
Dynamic Damping ◽  
The Galerkin Method ◽  
The Relationship

Abstract In this work, a parametric model for a frequency-up-conversion piezoelectric energy harvester (PEH) was developed based on the Galerkin method. The PEH is composed of a piezoelectric bimorph and a stopper, which was subjected to a harmonic excitation. Although backward coupling results in a structure dynamic damping, models with neglected backward coupling were often adopted to estimate the output power of a piezoelectric energy harvester. The purpose of this work is to examine the effect of backward coupling on the dynamic response and the output power generation for a frequency-up-conversion PEH. With the same base excitations, we compared the dynamics and output energies of two cases: (1) neglecting the backward coupling effect (BCE) in the model and (2) including the BCE in the model. To obtain the optimum gap with maximum output power, we studied the relationship between the output power and the gap of the steady-state solutions. From the analytical results, it was found that the BCE can be neglected as long as there is no impact or the output power is small. However, once impacts get involved, the piezoelectric backward effect dominates the total damping due to small mechanical damping which is true for most PEH. The backward coupling will significantly diminish both the vibration and output power. Therefore, if the BCE is neglected in an impact-driven frequency-up-conversion PEH, the simplified model will exaggerate the output power.

Joint Characteristic Effect on the Performance of Nonlinear Piezoelectric Energy Harvesters

2016 ◽  
Author(s):  
Kamal Jahani ◽  
Parisa Aghazadeh
Keyword(s):  
Energy Harvester ◽  
Lagrange Equation ◽  
Equations Of Motion ◽  
Maximum Output Power ◽  
Excitation Frequency ◽  
Numerical Approach ◽  
Maximum Output ◽  
Piezoelectric Energy ◽  
Joint Characteristic ◽  
Tip Mass

In this work, the effects of joint characteristics on the performance of a nonlinear piezoelectric energy harvester are investigated numerically. Large amplitude deflection unimorph beam with a tip mass and a nonlinear piezoelectric layer is considered as an energy harvester. By applying Euler-Lagrange equation and the Gauss’s law, mechanical and electrical equations of motion are obtained respectively, under two scenarios, i.e. with an ideal (rigid) joint and with a flexible one. A numerical approach is followed to investigate the effects of each nonlinear parameter of the harvester (stiffness, damping and piezoelectric coefficient) on harvested power. Results show that considering ideal joint between harvester and base structure leads to overestimating the maximum output power and the range of effective excitation frequency.

Harnessing Kinetic Energy From Human Motions With a High-Efficiency Wearable Electromagnetic Energy Harvester

2020 ◽  
Author(s):  
Yan Peng ◽  
Dong Zhang ◽  
Jun Luo ◽  
Shaorong Xie ◽  
Huayan Pu ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Flux Density ◽  
Energy Harvester ◽  
High Efficiency ◽  
Experimental Studies ◽  
Electromagnetic Energy ◽  
Maximum Output ◽  
Excellent Performance ◽  
Mass System ◽  
Current Output

Abstract Recent years have witnessed explosive increase in the number of wearable devices in the market and industry. However, hardly have these devices gained the ability to capture energy from hosts and then get self-charged. In this paper, we design and build a novel wearable electromagnetic energy harvester to scavenge the kinetic energy of human ankle during walking or running. The design is composed of mainly three parts: a spring-mass system, rolling ball pair and the electromagnetic transduction mechanism. The harvester adopts an array of alternating south- and north-pole magnets. This arrangement allows the array exhibits a unique phenomenon, i.e. abrupt magnetic flux density changes within the array. Because of this phenomenon, the harvester displays excellent performance such as relatively high voltage and high power output. We then conducted FEM analysis to validate the hypothetical abrupt flux density changes. A prototype was fabricated for experimental studies. We investigated open-circuit voltage output, current output, and power as well as charging performance into energy storage components. The result shows that harvester possesses excellent performance with the maximum output voltage of 8.64V, peak-peak power of 700mW and the highest volume power density of 24.9mW/cm3. The energy harvester, as a renewable portable power source, can be of great significance for powering smart wearable electronic devices and health care monitoring sensors.

Broadband Low-Frequency Vibration Energy Harvester with a Rolling Mass

2013 ◽  
Vol 404 ◽  
pp. 635-639 ◽  
Author(s):  
Xue Feng He ◽  
You Zhu ◽  
Yao Qing Cheng ◽  
Jun Gao
Keyword(s):  
Output Power ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Vibration Energy ◽  
Maximum Output ◽  
Vibration Energy Harvester ◽  
Low Frequency Vibration ◽  
Half Power

Richness of broadband low-frequency vibration energy in environemnts makes it significant to develop broadband low-frequency vibration energy harvesters. A vibration energy harvester composed of two symmetrical cantilevered piezoelectric bimorphs and a rolling mass in a guiding channel was proposed. A prototype of the vibration energy harvester with a rolling mass was assembled and tested. The base excitation caused the rolling mass to impact with two cantilevered bimorphs repeatedly and the impacts cause the bimorphs to vibrate dramatically. Experimental results show that maximum output power and corresponding excitation frequency increased with the amplitude of base acceleration. For the prototype, the maximum output power of a piezoelectric bimorph on a resistor with the resistance of 100 kΩ was 602 μW under base acceleration with the amplitude of 1.5 g and frequency of 37 Hz, and the half power bandwidth was about 13.5% or 5 Hz.

Multi-Stable Magnetic Spring-Based Energy Harvester Subject to Harmonic Excitation: Comparative Study and Experimental Evaluation

2018 ◽  
Author(s):  
Hieu Nguyen ◽  
Hamzeh Bardaweel
Keyword(s):  
Energy Harvesting ◽  
Kinetic Energy ◽  
Comparative Study ◽  
Experimental Evaluation ◽  
Chaotic Motion ◽  
Energy Harvester ◽  
Electric Energy ◽  
Harmonic Excitation ◽  
Jump Frequency ◽  
Piezoelectric Elements

The work presented here investigates a unique design platform for multi-stable energy harvesting using only interaction between magnets. A solid cylindrical magnet is levitated between two stationary magnets. Peripheral magnets are positioned around the casing of the energy harvester to create multiple stable positions. Upon external vibration, kinetic energy is converted into electric energy that is extracted using a coil wrapped around the casing of the harvester. A prototype of the multi-stable energy harvester is fabricated. Monostable and bistable configurations are demonstrated and fully characterized in static and dynamic modes. Compared to traditional multi-stable designs the harvester introduced in this work is compact, occupies less volume, and does not require complex circuitry normally needed for multi-stable harvesters involving piezoelectric elements. At 2.5g [m/s2], results from experiment show that the bistable harvester does not outperform the monostable harvester. At this level of acceleration, the bistable harvester exhibits intrawell motion away from jump frequency. Chaotic motion is observed in the bistable harvester when excited close to jump frequency. Interwell motion that yields high displacement amplitudes and velocities is absent at this acceleration.

Modelling of Mechanical Nonlinearity in an Electromagnetic Vibration Energy Harvester Using a Forced Duffing Equation

2012 ◽  
Author(s):  
S. D. Moss ◽  
L. A. Vandewater ◽  
S. C. Galea
Keyword(s):  
Output Power ◽  
Energy Harvester ◽  
Duffing Oscillator ◽  
Maximum Output Power ◽  
Vibration Energy ◽  
Maximum Output ◽  
Vibration Energy Harvesting ◽  
Vibration Energy Harvester ◽  
Homotopy Analysis ◽  
Wire Coil

This work reports on the modelling and experimental validation of a bi-axial vibration energy harvesting approach that uses a permanent-magnet/ball-bearing arrangement and a wire-coil transducer. The harvester’s behaviour is modelled using a forced Duffing oscillator, and the primary first order steady state resonant solutions are found using the homotopy analysis method (or HAM). Solutions found are shown to compare well with measured bearing displacements and harvested output power, and are used to predict the wideband frequency response of this type of vibration energy harvester. A prototype harvesting arrangement produced a maximum output power of 12.9 mW from a 12 Hz, 500 milli-g (or 4.9 m/s2) rms excitation.

scholarly journals Study on the Efficiency and Dynamic Characteristics of an Energy Harvester Based on Flexible Structure Galloping

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6548
Author(s):  
Peng Liao ◽  
Jiyang Fu ◽  
Wenyong Ma ◽  
Yuan Cai ◽  
Yuncheng He
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Physical Model ◽  
Energy Harvester ◽  
High Efficiency ◽  
Lateral Displacement ◽  
Maximum Output Power ◽  
Flexible Structure ◽  
Maximum Output ◽  
Cfd Numerical Simulation

According to the engineering phenomenon of the galloping of ice-coated transmission lines at certain wind speeds, this paper proposes a novel type of energy harvester based on the galloping of a flexible structure. It uses the tension generated by the galloping structure to cause periodic strain on the piezoelectric cantilever beam, which is highly efficient for converting wind energy into electricity. On this basis, a physical model of fluid–structure interaction is established, and the Reynolds-averaged Navier–Stokes equation and SST K -ω turbulent model based on ANSYS Fluent are used to carry out a two-dimensional steady computational fluid dynamics (CFD) numerical simulation. First, the CFD technology under different grid densities and time steps is verified. CFD numerical simulation technology is used to simulate the physical model of the energy harvester, and the effect of wind speed on the lateral displacement and aerodynamic force of the flexible structure is analyzed. In addition, this paper also carries out a parameterized study on the influence of the harvester’s behavior, through the wind tunnel test, focusing on the voltage and electric power output efficiency. The harvester has a maximum output power of 119.7 μW/mm3 at the optimal resistance value of 200 KΩ at a wind speed of 10 m/s. The research results provide certain guidance for the design of a high-efficiency harvester with a square aerodynamic shape and a flexible bluff body.

scholarly journals Adaptive Electromagnetic Energy Harvester for Mobile Devices

2020 ◽  
Author(s):  
Haziq Kamal ◽  
Peyman Moghadam
Keyword(s):  
Resonant Frequency ◽  
Mobile Devices ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Electromagnetic Energy ◽  
Major Drawback ◽  
Energy Harvesters ◽  
Limited Effectiveness ◽  
Energy Harvesting Devices ◽  
Ambient Excitation

<div>Advances in design and development of light-weight and low power wearable and mobile devices open up the possibility of lifetime extension of these devices from ambient sources through energy harvesting devices as opposed to periodically recharge the batteries. The most commonly available ambient energy source for mobile devices is Kinetic energy harvesters (KEH). The major drawback of the energy harvesters is limited effectiveness of harvesting mechanism near a fixed resonant frequency. It is difficult to harvest a reliable amount of energy from every forms of device motions with different excitation frequencies. To overcome this drawback, in this paper we propose an adaptive electromagnetic energy harvester which utilises spring characteristics to adapt its resonant frequency to match the ambient excitation frequency. This paper presents a prototype design and analysis of an adaptive electromagnetic energy harvester both in simulation and real. The harvester has tested using a specially designed experimental setup and compared with numerical simulations. The proposed solution generates 3.5 times higher maximum power over the default power output and 2.4 times higher maximum frequency compared to a fixed resonant frequency electromagnetic energy harvester.</div>

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