Study of Electromagnetic Vibration Energy Harvesting with Free/impact Motion for Low Frequency Operation PDF Download

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Languages : en
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Abstract: This paper presents study of an electromagnetic vibration energy harvesting configuration that can work effectively at low frequencies. Unlike the conventional form of vibration energy harvesters in which the mass is directly connected to a vibrating frame with spring suspension, in the proposed configuration a permanent magnet mass is allowed to move freely within a certain distance inside a frame-carrying coil and make impacts with spring end stops. The free motion distance allows matching lower vibration frequencies with an increase in the relative amplitude at resonance. Hence, significant power could be generated at low frequencies. A nonlinear mathematical model including impact and electromagnetic induction is derived. Study of the dynamic behaviour and investigation of the system performance is carried out with the aid of case study simulation. The proposed harvester shows a unique dynamic behaviour in which different ways of response of the internal relative oscillation appear over the range of input frequencies. A mathematical condition for the response type at which the higher relative amplitude appears is derived, followed by an investigation of the system resonant frequency and relative amplitude. The resonant frequency shows a dependency on the free motion distance as well as the utilized mass and spring stiffness. Simulation and experimental comparisons are carried out between the proposed harvester and similar conventional one tuned at the same input frequency. The power generated by the proposed harvesting configuration can reach more than 12 times at 11 Hz in the simulation case and about 10 times at 10 Hz in the experimental case. Simulation comparison also shows that this power magnification increases by matching lower frequencies which emphasize the advantages of the proposed configuration for low frequency operation. Highlights: We present an electromagnetic vibration energy harvester based on free/impact motion. The proposed harvester has a resonant behaviour. However, it shows a unique way of oscillation. Its resonant frequency can be shifted to lower range with an increase in the resonant relative amplitude Simulation and experimental comparison between the proposed harvester and similar conventional one shows its advantages at low frequencies.

Author: Ahmed Haroun
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659790997
Category :
Languages : en
Pages : 120

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Self-powering of wireless sensors and wireless micro-devices become an important issue nowadays. Problems associated with chemical batteries such as limited life time and minimization restrictions can be solved by using the approach of energy harvesting. In this work, a way of vibration energy harvesting utilizing combined free/impact motion associated with electromagnetic transduction is proposed and studied. The study include impact with soft and hard end stops. A harvester with soft end stops shows a unique resonant behavior. However, A micro energy harvester with hard end stops (FHH) shows certain characteristics that make it more appropriate for human powered devices. It can harvest significant amount of energy from human motion during daily activities. The performance of FHH is analyzed and tested with human body motion at different body locations during different daily activities.

Author: Alper Erturk
Publisher: John Wiley & Sons
ISBN: 1119991358
Category : Technology & Engineering
Languages : en
Pages : 377

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The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

Author: Mohamed Bendame
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Languages : en
Pages :

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The abundance of environmental kinetic energy combined with advances in the electronics and MEMS industries have opened a window of opportunities for the design and fabrication of self-powered, battery independent, low-power electronic devices. Kinetic energy harvesting, the process that captures vibrations from the environment or surrounding systems and converts them into electrical power, o ers the prospects of unlimited power for such systems. Vibration energy harvesters (VEHs) are vibration-based micro-power generators that utilize mechanical oscillators to capture ambient vibration energy and convert it into electrical power using one of three main transduction mechanisms, electromagnetic, electrostatic, or piezoelectric. A key feature of VEHs is their ability to harvest maximum environmental vibration energy from low amplitude and low frequency vibrations from a wide spectrum of frequencies. Traditional VEHs use linear mechanical oscillators as their harvesting element and are tuned to harvest environmental vibrations at resonance frequency present within the application environment. These VEHs are usually designed to harvest energy from high frequency vibrations in a narrow band in the vicinity of the natural frequency of the mechanical oscillator, and outside this narrow band of frequencies their output power is signi cantly reduced. In environments where ambient vibrations are random and only available at low frequencies, conventional harvesters prove to be ine ective. Although such devices are capable of generating power from vibrations with frequencies close to their resonance frequency, the need for harvesters that can harvest energy from broadband vibration sources has become an interesting research topic in recent years. To overcome the limitations associated with traditional vibration energy harvesters, nonlinear phenomena, such as hardening and softening nonlinearities, magnetic levitation, and pact have been sought as a solution to broadband vibration energy harvesting. In this thesis we aim to address this challenge by investigating a new architecture of an electromagnetic vibration energy harvester, the electromagnetic \Springless" vibration energy harvester (SVEH). The new architecture di ers from traditional harvester as it uses a double-impact oscillator as its harvesting element as opposed to the linear model. Experimental results show that the new SVEH is capable of harvesting vibration energies with frequencies as low as 5Hz and amplitudes as low as 0.05 g in a frequency band of about 8Hz. The harvester generates maximum output power of 12 mWatt from vibrations with amplitude of 0.5 g and an optimal load of 3.6 ohms. Experimental results also show that the "nonlinear" center frequency of the harvester is not constant, as in the case of conventional harvesters, but depends on the amplitude and frequency of the external vibrations and whether the harvester is operated in the vertical or horizontal position. Experimental as well as the numerical frequency response curves of the SVEH also show the existence of hardening nonlinearity in the horizontal con guration and softening nonlinearity in the vertical con guration in the system. The hardening e ect allows harvesting of energy in the high frequency spectrum, about 25 Hz and a bandwidth of 7 Hz, while the softening e ect allows harvesting at the lower end of the frequency spectrum, which is around 5 Hz and a bandwidth of 8 Hz. Models of the SVEH in the vertical and horizontal con gurations were developed and nonlinear numerical and analytical methods were used to analyze the system to gain a deeper understanding of the system's behavior. The experimental data is then used to validate the models. The harvester's ability to harvest vibration energy from low frequency ( 25Hz) and low amplitude vibrations ( 0:5g) in a wide band ( 5Hz) is one of the unique features of the SVEH demonstrated in this work.

Author: Dirk Spreemann
Publisher: Springer Science & Business Media
ISBN: 9400729448
Category : Technology & Engineering
Languages : en
Pages : 198

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Electromagnetic vibration transducers are seen as an effective way of harvesting ambient energy for the supply of sensor monitoring systems. Different electromagnetic coupling architectures have been employed but no comprehensive comparison with respect to their output performance has been carried out up to now. Electromagnetic Vibration Energy Harvesting Devices introduces an optimization approach which is applied to determine optimal dimensions of the components (magnet, coil and back iron). Eight different commonly applied coupling architectures are investigated. The results show that correct dimensions are of great significance for maximizing the efficiency of the energy conversion. A comparison yields the architectures with the best output performance capability which should be preferably employed in applications. A prototype development is used to demonstrate how the optimization calculations can be integrated into the design–flow. Electromagnetic Vibration Energy Harvesting Devices targets the designer of electromagnetic vibration transducers who wishes to have a greater in-depth understanding for maximizing the output performance.

Author: Bryn Edwards
Publisher:
ISBN:
Category : Electromagnetic induction
Languages : en
Pages : 312

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Harvesting low frequency vibration energy poses significant challenges: difficulty in resonant frequency matching, large displacement amplitude and low electromechanical coupling. The aim of this project was to develop, model and experimentally validate a new vibration energy harvesting structure utilising a novel mechanical frequency up-conversion method to address these challenges. A new method for mechanical frequency up-conversion was proposed leveraging a non-linear effect which has not previously been studied in energy harvesting. In this method an oscillation in a cantilever beam may be induced at a higher frequency than both the cantilever resonant frequency and excitation frequency through impact with a high restitution end-stop placed near the neutral position of the beam, when exposed vibration excitations below the resonant frequency of the cantilever. A structure to implement this method was developed, mathematically modelled and experimentally validated. Simulation indicated that, relative to a simple cantilever structure, the RMS velocity of the proof mass may be increased, while the displacement of the mass is simultaneously decreased, resulting in an improved energy density and this was confirmed by experimental results. The frequency up-conversion mechanism was used to implement an energy harvester using electromagnetic transduction. The energy harvester was modelled mathematically and this model was validated experimentally. Simulation results suggested a potential increase in the power output of the harvester at low electromagnetic damping factors and were confirmed by experimental results. The output voltage was, however, very low and was determined to be insufficient for a stand-alone harvester. Adopting the frequency up-conversion mechanism using piezoelectric transduction was considered and a new soft piezoelectric transducer utilising PVDF and a PDMS central shim was proposed, modelled and experimentally investigated. The transducer demonstrated potential for high voltage outputs, however at the cost of low power output and high resonant frequency. It was therefore determined unsuitable for implementation in the mechanical frequency upconversion mechanism. Finally a new approach using a hybrid electromagnetic-piezoelectric scheme was investigated and a structural implementation was proposed, modelled and experimentally validated. With this structure, the high power output of the electromagnetic transducer was retained, while an auxiliary output at a high voltage level, suitable for powering a low-power conditioning circuit, was produced by the piezoelectric transducer.

Author: P. L. Green
Publisher:
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Category :
Languages : en
Pages :

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The concept of harvesting electrical energy from ambient vibration sources has been a popular topic of research in recent years. The motivation behind this research is largely due to recent advancements in microelectromechanical systems (MEMS) technology - specifically the construction of small low powered sensors which are capable of being placed in inaccessible or hostile environments. The main drawback with these devices is that they require an external power source. For example, if one considers large networks of low powered sensors (such as those which may be attached to a bridge as part of a structural health monitoring system) then one can envisage a scenario where energy harvesters are used to transfer the vibration energy of the bridge into electrical energy for the sensors. This would alleviate the need for batteries which, in this scenario, would be difficult to replace. Initial energy harvester designs suffered from a major flaw: they were only able to produce useful amounts of power if they were excited close to their resonant frequency. This narrow bandwidth of operation meant that they were poorly suited to harvesting energy from ambient vibration sources which are often broadband and have time dependent dominant frequencies. This led researchers to consider the concept of nonlinear energy harvesting - the hypothesis that the performance of energy harvesters could be improved via the deliberate introduction of dynamic nonlinearities. This forms the main focus of the work in this thesis. The first major part of this work is concerned with the development of an experimentally validated physical-law based model of an electromagnetic energy harvester with Duffing-type nonlinearities. To this end, a self-adaptive differential evolution vi (SADE) algorithm is used in conjunction with experimental data to estimate the parameters needed to accurately model the behaviour of the device. During this investigation it is found that the response of the energy harvesting device in question is very sensitive to the effects of friction. Consequently, a detailed study is undertaken with the aim of finding whether the model performance could be improved by accounting for this complex nonlinear phenomenon. After investigating several different friction models, a reliable and extensively validated digital model of a nonlinear energy harvesting device is realised. With the appropriate equations of motion identified, analytical approximation methods are used to analyse the response of the device to sinusoidal excitations. The motivation for the second main part of this work arises from the fact that ambient excitations are often stochastic in nature. As a result, much of the work in this section is directed towards gaining an understanding of how nonlinear energy harvesters respond to random excitations. This is an interesting problem because, as a result of the random excitation, it is impossible to say exactly how such a device will respond - the problem must be tackled using a probabilistic approach. To this end, the Fokker-Planck-Kolmogorov (FPK) equation is used to develop probability density functions describing how the nonlinear energy harvester in question responds to Gaussian white noise excitations. By conducting this analysis, previously unrecognised benefits of Duffing-type nonlinearities in energy harvesters are identified along with important findings with regards to device electrical optimisation. As for friction effects, the technique of equivalent linearisation is employed alongside known solutions of the FPK equation to develop expressions approximating the effect of friction on randomly excited energy harvesters. These results are then validated using Monte-Carlo methods thus revealing important results about the interaction between Duffing-type and friction nonlinearities. Having investigated sinusoidal and random excitations, the final part of this work focuses on the application of nonlinear energy harvesting techniques to real energy harvesting scenarios. Excitation data from human walking motion and bridge vibrations is used to excite digital models of a variety of recently proposed nonlinear energy harvesters. This analysis reveals important information with respect to how well energy harvesting solutions developed under the assumption of Gaussian white noise excitations can be extended to real world scenarios.

Author: Karim El-Rayes
Publisher:
ISBN:
Category :
Languages : en
Pages : 68

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The demand for portable permanent sources of electrical energy increases every day to power portable or non-accessible devices. Energy harvesting from vibrations offers a non-traditional source of energy. It is renewable and prevailing, since nature around is rich in kinetic energy that can be harvested. In this work, we have developed two mechanisms to harvest energy from low-frequency vibrations present in nature using electromagnetic transduction. The harvesting mechanisms use a mass-on-spring mechanical oscillator to capture kinetic energy from a host body. Prototypes embodying the two harvesting mechanisms were fabricated and tested. We identi ed the system parameters of the harvester prototypes and generated their frequency-response curves. We analyzed the results using and compared them with mathematical models of the system dynamics to characterize the harvesters' performance including their output power, center frequency, and harvesting bandwidth. We were successful in demonstrating energy harvesters that can harvest low-frequency vibration with center frequencies in the range of 8-14 Hz, harvesting bandwidth in the range of 8-12Hz, and output power on the order of 1mW. The realized harvesters are relatively small, a few inches in dimension, and light, a few tens of grams in mass. We also introduced a novel electromagnetic transduction mechanism that can be used in harvesting low-frequency vibrations.

Author: Ruize Xu (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 195

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Vibration energy harvesters work effectively only when the operating conditions match with the available vibration source. Typical resonating MEMS structures cannot be used with low-frequency, low-amplitude and unpredictable nature of ambient vibrations. Bi-stable nonlinear oscillator based energy harvesters are developed for lowering the operating frequency while widening the bandwidth, and are realized at MEMS scale for the first time. This design concept does not rely on the resonance of the MEMS structure but operates with the large snapping motion of the beam at very low frequencies when proper conditions are provided to overcome the energy barrier between the two energy wells of the structure. A fully functional piezoelectric MEMS energy harvester is designed, monolithically fabricated and tested. An electromechanical lumped parameter model is developed to analyze the nonlinear dynamics and to guide the design of the multi-layer buckled beam structure. Residual stress induced buckling is achieved through the progressive control of the deposition along the fabrication steps. Static surface profile of the released device shows bi-stable buckling of 200 [mu]m which matches very well with the design. Dynamic testing demonstrates the energy harvester operates with 35% bandwidth under 70Hz at 0.5g, operating conditions that have not been met before by MEMS vibration energy harvesters.

Author: Amin Abedini
Publisher:
ISBN:
Category : Energy harvesting
Languages : en
Pages : 204

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Book Description
Ambient energy harvesting has attracted significant attention over the last years for applications such as wireless sensors, implantable devices, health monitoring systems, and wearable devices. The methods of vibration-to-electric energy conversion can be included in the following categories: electromagnetic, electrostatic, and piezoelectric. Among various techniques of vibration-based energy harvesting, piezoelectric transduction method has received the most attention due to the large power density of the piezoelectric material and its simple architectures. In contrast to electromagnetic energy harvesting, the output voltage of a piezoelectric energy harvester is high, which can charge a storage component such as a battery. Compared to electrostatic energy harvester, the piezoelectric energy harvester does not require an external voltage supply. Also, piezoelectric harvesters can be manufactured in micro-scale, where they show better performance compared to other energy harvesters, owing to the well-established thick-film and thin-film fabrication techniques. The main drawback of the linear piezoelectric harvesters is that they only retrieve energy efficiently when they are excited at their resonance frequencies, which are usually high, while they are less efficient when the excitation frequency is distributed over a broad spectrum or is dominant at low frequencies. High-frequency vibrations can be found in machinery and vehicles could be used as the energy source but, most of the vibration energy harvesters are targeting at low-frequency vibration sources which are more achievable in the natural environment. One way to overcome this limitation is by using the frequency-up-conversion technology via impacts, where the source of the impacts can be one or two stoppers or more massive beams. The impact makes the piezoelectric beam oscillate in its resonance frequency and brings nonlinear behavior into the system. The goal of this research is to enhance the piezoelectric harvester's energy retrieving performance from ambient vibrations with low or varying frequencies. In this work, impact-based piezoelectric energy harvesters were studied by discontinuous mapping dynamics. Discontinuous dynamics has been extensively applied in mechanical dynamics and physics field. Since the nature of the most environmental vibrations is periodic, periodic motions of the impact-based piezoelectric harvester were studied. Four different possible motion phases have been identified and categorized based on the performance of the output energy of the system. Many periodic motions are possible depending on the physical properties of the energy harvester setup. So far, we studied three different periodic motions of two beams interacting with each others, where period-1 and period-2 motions of the system are predicted. The stability of the system were analyzed and bifurcation graphs for each periodic motions were presented.