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

Author(s):  
Hieu Nguyen ◽  
Hamzeh Bardaweel

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.

2015 ◽  
Vol 25 (12) ◽  
pp. 1550171 ◽  
Author(s):  
Mattia Coccolo ◽  
Grzegorz Litak ◽  
Jesús M. Seoane ◽  
Miguel A. F. Sanjuán

In this paper, we study the vibrational resonance (VR) phenomenon as a useful mechanism for energy harvesting purposes. A system, driven by a low frequency and a high frequency forcing, can give birth to the vibrational resonance phenomenon, when the two forcing amplitudes resonate and a maximum in amplitude is reached. We apply this idea to a bistable oscillator that can convert environmental kinetic energy into electrical energy, that is, an energy harvester. Normally, the VR phenomenon is studied in terms of the forcing amplitudes or of the frequencies, that are not always easy to adjust and change. Here, we study the VR generated by tuning another parameter that is possible to manipulate when the forcing values depend on the environmental conditions. We have investigated the dependence of the maximum response due to the VR for small and large variations in the forcing amplitudes and frequencies. Besides, we have plotted color coded figures in the space of the two forcing amplitudes, in which it is possible to appreciate different patterns in the electrical power generated by the system. These patterns provide useful information on the forcing amplitudes in order to produce the optimal electrical power.


Author(s):  
H. Li ◽  
S. D. Hu ◽  
H. S. Tzou

Piezoelectric energy harvesting has experienced significant growth over the past few years. Various harvesting structures have been proposed to convert ambient vibration energies to electrical energy. However, these harvester’s base structures are mostly beams and some plates. Shells have great potential to harvest more energy. This study aims to evaluate a piezoelectric coupled conical shell based energy harvester system. Piezoelectric patches are laminated on the conical shell surface to convert vibration energy to electric energy. An open-circuit output voltage of the conical energy harvester is derived based on the thin-shell theory and the Donnel-Mushtari-Valsov theory. The open-circuit voltage and its derived energy consists of four components respectively resulting from the meridional and circular membrane strains, as well as the meridional and circular bending strains. Reducing the surface of the harvester to infinite small gives the spatial energy distribution on the shell surface. Then, the distributed modal energy harvesting characteristics of the proposed PVDF/conical shell harvester are evaluated in case studies. The results show that, for each mode with unit modal amplitude, the distribution depends on the mode shape, harvester location, and geometric parameters. The regions with high strain outputs yield higher modal energies. Accordingly, optimal locations for the PVDF harvester can be defined. Also, when modal amplitudes are specified, the overall energy of the conical shell harvester can be calculated.


Author(s):  
Timothy Reissman ◽  
Ephrahim Garcia

This work details the implantation process of an energy harvester platform within a Manduca sexta Hawkmoth for the purpose of creating a cyborg insect. Also included is an evaluation of energy harvesting with respect to present lightweight battery technology and the magnitudes of ambient energy available for the cyborg insect application. Specific emphasis is given to kinetic energy harvester development, with theory and fabrication of the devices detailed.


2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Giovanni Caruso

In this paper, an adaptive electromagnetic energy harvester is proposed and analyzed. It is composed of an oscillating mass equipped with an electromagnetic transducer, whose pins are connected to a resonant resistive–inductive–capacitive electric circuit in order to increase its effective bandwidth. Closed-form expressions for the optimal circuit parameters are presented, which maximize the power harvested by the device under harmonic excitation. The harvesting efficiency, defined as the ratio between the harvested power and the power absorbed by the oscillating device, is also reported. It is used as an alternative objective function for the optimization of the harvester circuit parameters.


2016 ◽  
Vol 40 (2) ◽  
pp. 221-230
Author(s):  
Yu Zhang ◽  
Riccardo De Rosa ◽  
Jingyi Zhang ◽  
Mariam Alameri ◽  
Kefu Liu

In this study, an energy harvesting device based on a nonlinear vibration absorber is developed to achieve two objectives: vibration suppression and energy harvesting in a wideband manner. First, the proposed design is described. Next, the system modeling is addressed. The parameter characterization is presented. Then, the performance of the nonlinear vibration absorber is tested by sweeping harmonic excitation. The testing results have shown that the device can suppress vibration and convert vibration energy into electric energy in a broadband manner.


Author(s):  
Melody Coffey ◽  
Raymond Dalke ◽  
Ryian Williams ◽  
Devyn Sutton ◽  
Jan Brink ◽  
...  

Transportation vehicles traveling on busy roads and highways waste an appreciable amount of their kinetic energy. The lost energy dissipation is due to many factors such as: the friction due to braking, the friction of the tires on the road, the friction of the vehicle body against the surrounding air, and the friction due to the engine’s moving parts. In an effort to save some of this lost energy, it is possible to harvest it through pneumatic and mechanical devices built into the road, especially on highly traffic highways. With over 1 billion cars in the world, there is a huge potential for tapping into the lost energy, and harvesting it for another use. This technical paper focuses on designing a pneumatic and mechanical system that collects the lost kinetic energy of multiple passing cars. A new energy harvesting system utilizing pneumatic and mechanical components has been developed. In this system, a vehicle’s tires pass over a pneumatic manifold system equipped with exciter keys. These keys are depressed and activate a pneumatic system to compress air. Each exciter key is coupled to a connecting rod and piston assembly. The compressed air generated by many exciter keys is then collected in an air tank and channeled to a pneumatic motor. The pneumatic motor transmits then a rotational motion to an electricity generator that produces electric energy. The electric energy can be stored into a series of batteries. The modular pneumatic manifold systems would be located where car drivers encounter deceleration ramps, when approaching a stop sign, or entering a toll booth plaza, etc. The pneumatic system was designed using a computer drawing CAD software. The vehicle’s kinetic energy losses are thoroughly analyzed and their distribution is comprehensively determined using the first principle of thermodynamics, and the thermodynamics theory for compressed air. Energy losses to the system keys and springs, and different friction losses are also determined. A pneumatic model of the manifold, and piping connections to the air tank has been programmed using a pneumatic software for modeling and simulation. An economic viability study of such systems has also been performed. Parameters such as the number of passing cars and the number of strokes on the exciter keys necessary to fill an air tank are determined. A physical prototype of the modular manifold has been built, and experimental measurements are expected to be performed in an upcoming second phase of the project. It is envisioned that such harvesting energy systems can be used to produce energy locally in remote road areas to power stop lights, or street lights. This type of system can also be adapted to be used with other transportation systems such as trains and buses to produce electricity for their respective stations when traffic is heavy.


Author(s):  
Alper Erturk ◽  
Ho-Yong Lee ◽  
Daniel J. Inman

Piezoelectric materials have received the most attention for vibration-to-electricity conversion over the last decade. Harmonic excitation is the most commonly investigated form of excitation in piezoelectric energy harvesting and it can be divided into two subgroups as resonant and off-resonant excitations. Although resonant excitation is preferred for extracting the maximum electrical power output from the device, there are several practical cases where it is not possible to excite the energy harvester at its resonance frequency (e.g. varying frequency excitations or very low frequency excitations where the input frequency is much lower than the fundamental resonance frequency). Several researchers have used soft piezoceramics (e.g. PZT-5A and PZT-5H) for power generation under resonant excitation. Typically, these soft piezoceramics have larger piezoelectric strain constant and larger elastic compliance compared to hard piezoceramics (e.g. PZT-4 and PZT-8). However, it is known that hard piezoceramics can have an order of magnitude larger mechanical quality factor compared to soft piezoceramics. Consequently, hard piezoceramics can generate more power under resonant excitation even though researchers have mostly focused on the soft piezoceramics. On the other hand, soft piezoceramics can generate more power for low frequency excitation below the resonance frequency due to their large effective piezoelectric stress constants. This difference is also the case for soft and hard single crystals (e.g. soft PMN-PZT versus hard PMN-PZT-Mn). In addition, single crystals can generate more power than ceramics at low off-resonant frequencies due to their large dynamic flexibilities (which is related to their large elastic compliances). This work investigates the specific advantages of soft and hard piezoceramics and single crystals for vibration-based energy harvesting. An experimentally validated piezoelectric energy harvester model is used to compare the power generation performances of soft and hard ceramics as well as soft and hard single crystals. The soft and the hard piezoceramics considered in this work are PZT-5H and PZT-8, respectively, while the soft and the hard single crystals considered here are PMN-PZT and PMN-PZT-Mn, respectively.


2021 ◽  
Author(s):  
Christopher Beach ◽  
Alex Casson

Energy harvesting from human motion can reduce reliance on battery recharging in wearable devices and lead to improved adherence. However, to date, studies estimating energy harvesting potential have largely focused on small scale, healthy, population groups in laboratory settings rather than free-living environments with population level participant numbers. Here, we present the largest scale investigation into energy harvesting potential by utilising the activity data collected in the UK Biobank from over 67,000 participants. This paper presents detailed stratification into how the day of the week and participant age affect harvesting potential, as well as how the presence of conditions (such as diabetes, which we investigate here), may affect the expected energy harvester output. We process accelerometery data using a kinetic energy harvester model to investigate power output at a high temporal resolution. Our results identify key differences between the times of day when the power is available and an inverse relationship between power output and participant age. We also identify that the presence of diabetes substantially reduces energy harvesting output, by over 21%. The results presented highlight a key challenge in wearable energy harvesting: that wearable devices aim to monitor health and wellness, and energy harvesting aims to make devices more energy autonomous, but the presence of medical conditions may lead to substantially lower energy harvesting potential. The findings indicate how it is challenging to meet the required power budget to monitor diseases when energy autonomy is a goal.


Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1300
Author(s):  
Xiang Li ◽  
Jinpeng Meng ◽  
Chongqiu Yang ◽  
Huirong Zhang ◽  
Leian Zhang ◽  
...  

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


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