Ambient vibrations piezoelectric harvester array with discrete multiple low frequencies (original) (raw)
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Piezoelectric Vibration Energy Harvesters
2018
Energy harvesting is the process of collecting low-level ambient energy and converting it into electrical energy to be used for powering miniaturized autonomous devices, sensor networks, wearable electronics or Internet-of-Things components. The use of the pervasive kinetic energy, converted into electrical energy, is of special interest in this frame. The possibility to use bimorph piezoelectric cantilevers to convert ambient vibrations to electrical energy is therefore thoroughly analyzed in this work. A reliable modelling tool for optimizing the design of the miniature harvesters to be used in a broad frequency range, while maximizing the obtained powers, is hence needed. The problem complexity is induced by the necessity to simulate the dynamic response of the considered harvesting devices via a coupled electromechanical model. The recently developed comprehensive coupled analytical model based on distributed parameters is thus used as a benchmark to verify and tune suitable fin...
A retrofitted energy harvester for low frequency vibrations
Smart Materials and Structures, 2012
Piezoelectric-based energy harvesting is an efficient way to convert ambient vibration energy into usable electric energy. However, its output power drops steeply with reducing excitation frequency. To improve the harvesting performance at low frequencies, a multi-impact harvester is proposed in this paper. The proposed design consists of a hung mass and two stiff piezoelectric cantilever beams. A series of impacts between the mass and cantilever beams are involved during the vibration of the mass, which triggers high frequency vibrations on the cantilever beams. Four equations of motion corresponding to different system statuses are presented to simulate the vibration of the harvester. Based on the linear piezoelectric theory, a distributed-parameter electromechanical model is used for the bimorph cantilever beam and its output power is calculated. For comparison, a conventional cantilever-beam-based harvester and a single-impact harvester are introduced and their output powers are also calculated. Under the same sinusoidal excitation, the modeling result shows that the power of the proposed harvester is more than three times larger than the ones from the conventional cantilever beam harvester and the single-impact harvester. The multi-impact harvester also occupies less space than the conventional one. A parametric study is presented in this paper for the multi-impact harvester considering different external resistances, hung masses, cantilever beam thicknesses and excitation frequencies.
A Review of Vibration-Based Piezoelectric Energy Harvesters.
International Journal of Engineering Sciences & Research Technology, 2014
Piezoelectric energy harvesting technology has received a great attention during the last decade to activate low power microelectronic devices. Piezoelectric cantilever beam energy harvesters are commonly used to convert ambient vibration into electrical energy. In this paper we reviewed the work carried out by researchers during the last ten years. The improvements in experimental results obtained in the vibration-based piezoelectric energy harvesters show very good scope for piezoelectric harvesters in the field of power in the near future.
A novel two-degrees-of-freedom piezoelectric energy harvester
Journal of Intelligent Material Systems and Structures, 2013
Energy harvesting from ambient vibrations using piezoelectric effect is a promising alternative solution for powering small electronics such as wireless sensors. A conventional piezoelectric energy harvester usually consists of a cantilevered beam with a proof mass at its free end. For such a device, the second resonance of the piezoelectric energy harvester is usually ignored because of its high frequency as well as low response level compared to the first resonance. Hence, only the first mode has been frequently exploited for energy harvesting in the reported literature. In this article, a novel compact piezoelectric energy harvester using two vibration modes has been developed. The harvester comprises one main cantilever beam and an inner secondary cantilever beam, each of which is bonded with piezoelectric transducers. By varying the proof masses, the first two resonant frequencies of the harvester can be tuned close enough to achieve useful wide bandwidth. Meanwhile, this compa...
A Multiple Direction Broad Frequency Band Piezoelectric Energy Harvester
A multiple direction broad frequency band piezoelectric energy harvester is proposed for harvesting ambient vibration energy with a variable frequency in different directions. The harvester is composed of eight cantilevers which point to different direction. The single cantilever consists of a base, two ceramic pieces and a proof mass which would be glued together. The finite element model of the harvester is constructed and the effects of structure parameters of the harvester on effective work frequency, electricity generating capability and maximal stress value are analyzed. The results indicate the effective work frequency scope of the harvester is about 13-20Hz. The harvester can harvest relatively more energy in different excitation. The electric potential of a harvester is about 720.136V at the ambient load of 400Pa and the harvester is well suited for some wireless communication systems.
Energies, 2019
Harvesting electricity from low frequency vibration sources such as human motions using piezoelectric energy harvesters (PEH) is attracting the attention of many researchers in recent years. The energy harvested can potentially power portable electronic devices as well as some medical devices without the need of an external power source. For this purpose, the piezoelectric patch is often mechanically attached to a cantilever beam, such that the resonance frequency is predominantly governed by the cantilever beam. To increase the power generated from vibration sources with varying frequency, a multiresonant PEH (MRPEH) is often used. In this study, an attempt is made to enhance the performance of MRPEH with the use of a cantilever beam of optimised shape, i.e., a cantilever beam with two triangular branches. The performance is further enhanced through optimising the design of the proposed MRPEH to suit the frequency range of the targeted vibration source. A series of parametric studies were first carried out using finite-element analysis to provide in-depth understanding of the effect of each design parameters on the power output at a low frequency vibration. Selected outcomes were then experimentally verified. An optimised design was finally proposed. The results demonstrate that, with the use of a properly designed MRPEH, broadband energy harvesting is achievable and the efficiency of the PEH system can be significantly increased.
A review of power harvesting from vibration using piezoelectric materials
Shock and Vibration Digest, 2004
The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, there has been a surge of research in the area of power harvesting. This increase in research has been brought on by the modern advances in wireless technology and low-power electronics such as microelectromechanical systems. The advances have allowed numerous doors to open for power harvesting systems in practical real-world applications. The use of piezoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramatic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, vice versa, to convert an applied electrical potential into mechanical strain. This property provides these materials with the ability to absorb mechanical energy from their surroundings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. While piezoelectric materials are the major method of harvesting energy, other methods do exist; for example, one of the conventional methods is the use of electromagnetic devices. In this paper we discuss the research that has been performed in the area of power harvesting and the future goals that must be achieved for power harvesting systems to find their way into everyday use.
2013
The desire to reduce power consumption of current integrated circuits has led design engineers to focus on harvesting energy from free ambient sources such as vibrations. The energy harvested this way can eliminate the need for battery replacement, particularly, in low-energy remote sensing and wireless devices. Currently, most vibration-based energy harvesters are designed as linear resonators, therefore, they have a narrow resonance frequency. The optimal performance of such harvesters is achieved only when their resonance frequency is matched with the ambient excitation. In practice, however, a slight shift of the excitation frequency will cause a dramatic reduction in their performance. In the majority of cases, the ambient vibrations are totally random with their energy distributed over a wide frequency spectrum. Thus, developing techniques to extend the bandwidth of vibration-based energy harvesters has become an important field of research in energy harvesting systems. This thesis first reviews the broadband vibration-based energy harvesting techniques currently known in some detail with regard to their merits and applicability under different circumstances. After that, the design, fabrication, modeling and characterization of three new piezoelectric-based energy harvesting mechanism, built typically for rotary motion applications, is discussed. A step-by-step procedure is followed in order to broaden the bandwidth of such energy harvesters by introducing a coupled spring-mass system attached to a PZT beam undergoing rotary motion. It is shown that the new strategies can indeed give rise to a wide-band frequency response making it possible to fine-tune their dynamical response. The numerical results are shown to be in good agreement with the experimental data as far as the frequency response is concerned.
Modeling, validation, and performance of low-frequency piezoelectric energy harvesters
Analytical and finite element electromechanical models that take into account the fact that the piezoelectric sheet does not cover the whole substrate beam are developed. A linear analysis of the analytical model is performed to determine the optimal load resistance. The analytical and finite element models are validated with experimental measurements. The results show that the analytical model that takes into account the fact that the piezoelectric patch does not cover the whole beam predicts accurately the experimental measurements. The finite element results yield a slight discrepancy in the global frequency and a slight overestimation in the value of the harvested power at resonance. On the contrary, using an approximate analytical model based on mode shapes of the full covered beam leads to erroneous results and overestimation of the global frequency as well as the level of harvested power. In order to design enhanced piezoelectric energy harvesters that can generate energy at low-frequency excitations, further analysis is performed to investigate the effects of varying the length of the piezoelectric material on the natural frequency and the performance of the harvester. The results show that there is a compromise between the length of the piezoelectric material, the electrical load resistance, and the available excitation frequency. By quantifying this compromise, we optimize the performance of beammass systems to efficiently harvest energy from a specified low frequency of the ambient vibrations.
A Self-Sufficient and Frequency Tunable Piezoelectric Vibration Energy Harvester
In this paper, a novel smart vibration energy harvester (VEH) is presented. The harvester automatically adjusts its natural frequency to stay in resonance with ambient vibration. The proposed harvester consists of two piezoelectric cantilever beams, a tiny piezomotor with a movable mass attached to one of the beams, a control unit, and electronics. Thanks to its self-locking feature, the piezomotor does not require energy to fix its movable part, resulting in an improvement in overall energy demand. The operation of the system is optimized in order to maximize the energy efficiency. At each predefined interval, the control unit wakes up, calculates the phase difference between two beams, and if necessary, actuates the piezomotor to move its mass in the appropriate direction. It is shown that the proposed tuning algorithm successfully increases the fractional bandwidth of the harvester from 4% to 10%. The system is able to deliver 83.4% of the total harvested power into usable electrical power, while the piezomotor uses only 2.4% of the harvested power. The presented efficient, autotunable, and self-sufficient harvester is built using off-the-shelf components and it can be easily modified for wide range of applications.