A 3D Multidirectional Piezoelectric Energy Harvester using Rope-Driven Mechanism for Low Frequency and Ultralow Intensity Vibration Environment

Author(s):  
Jinhui Zhang ◽  
Maoyu Lin ◽  
Wei Zhou ◽  
Lihua Tang ◽  
Lifeng Qin

Abstract Though numerous piezoelectric vibration energy harvesters (PVEHs) have been designed and investigated to provide power supply for wireless sensors or wearable devices, it remains a challenge for traditional PVEHs to work effectively in an environment of low frequency, low acceleration and multidirectional vibrations. This work presents a PVEH using a low-frequency energy-capturing resonant system formed by a rolling ball in a hemispherical shell and driven by a rope. Due to the symmetry of the sphere, the ball can be excited at multiple directions in 3D space, and the piezoelectric beam can be pulled by the ball through a rope in multiple directions. Thus, the efficient multidirectional energy harvesting under low frequency (< 10 Hz) and ultralow intensity (< 0.1 g) vibrations could be realized. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed PVEH. The results show that the proposed PVEH has a potential to collect energy in any direction in 3D space, and could achieve a good angle bandwidth with 360° for φ and 240° for β under the excitation of a = 0.04 g, f = 6.8 Hz with the acceleration defined in the spherical coordinate system. The developed PVEH can generate 6.5 μW under a low-intensity excitation (0.03 g), and the normalized power density can reach 22.63 μW/(cm3g2Hz). Moreover, the minimum start-up acceleration analysis of the proposed PVEH indicates that the PVEH can capture multidirectional energy from vibrations as low as 0.01 g. In addition, both simulation and experimental study on rope redundancy and ball mass show that they can be used to adjust the device performance easily without structure re-fabrication. Overall, this study demonstrates a new mechanism that could effectively harvest low frequency, ultralow intensity and multidirectional vibration

Author(s):  
M. H. Ansari ◽  
M. Amin Karami

A three dimensional piezoelectric vibration energy harvester is designed to generate electricity from heartbeat vibrations. The device consists of several bimorph piezoelectric beams stacked on top of each other. These horizontal bimorph beams are connected to each other by rigid vertical beams making a fan-folded geometry. One end of the design is clamped and the other end is free. One major problem in micro-scale piezoelectric energy harvesters is their high natural frequency. The same challenge is faced in development of a compact vibration energy harvester for the low frequency heartbeat vibrations. One way to decrease the natural frequency is to increase the length of the bimorph beam. This approach is not usually practical due to size limitations. By utilizing the fan-folded geometry, the natural frequency is decreased while the size constraints are observed. The required size limit of the energy harvester is 1 cm by 1 cm by 1 cm. In this paper, the natural frequencies and mode shapes of fan-folded energy harvesters are analytically derived. The electro-mechanical coupling has been included in the model for the piezoelectric beam. The design criteria for the device are discussed.


2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Xiaokun Ma ◽  
Andrew Wilson ◽  
Christopher D. Rahn ◽  
Susan Trolier-McKinstry

Piezoelectric energy harvesters typically perform poorly in the low frequency, low amplitude, and intermittent excitation environment of human movement. In this paper, a piezoelectric compliant mechanism (PCM) energy harvester is designed that consists of a polyvinylidene diflouoride (PVDF) unimorph clamped at the base and attached to a compliant mechanism at the tip. The compliant mechanism has two flexures that amplify the tip displacement to produce large motion of a proof mass and a low frequency first mode with an efficient (nearly quadratic) shape. The compliant mechanism is fabricated as a separate, relatively rigid frame with flexure hinges, simplifying the fabrication process, and surrounding and protecting the piezoelectric unimorph. The bridge structure of the PCM also self-limits the response to large amplitude impacts, improving the device robustness. Experiments show that the compliant hinge stiffness can be carefully tuned to approach the theoretical high power output and mode shape efficiency.


Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2770 ◽  
Author(s):  
Iman Izadgoshasb ◽  
Yee Lim ◽  
Ricardo Vasquez Padilla ◽  
Mohammadreza Sedighi ◽  
Jeremy Novak

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.


2018 ◽  
pp. 826-862
Author(s):  
Abdessattar Abdelkefi

There exist numerous low-frequency excitation sources, such as walking, breathing, and ocean waves, capable of providing viable amounts of mechanical energy to power many critical devices, including pacemakers, cell phones, MEMS devices, wireless sensors, and actuators. Harvesting significant energy levels from such sources can only be achieved through the design of devices capable of performing effective energy transfer mechanisms over low frequencies. In this chapter, two concepts of efficient low-frequency piezoelectric energy harvesters are presented, namely, variable-shaped piezoelectric energy harvesters and piezomagnetoelastic energy harvesters. Linear and nonlinear electromechanical models are developed and validated in this chapter. The results show that the quadratic shape can yield up to two times the energy harvested by a rectangular one. It is also demonstrated that depending on the available excitation frequency, an enhanced energy harvester can be tuned and optimized by changing the length of the piezoelectric material or by changing the distance between the two tip magnets.


Author(s):  
Junyi Cao ◽  
Shengxi Zhou ◽  
Daniel J. Inman

This paper investigates the nonlinear dynamic characteristics of a magnetically coupled piezoelectric energy harvesters under low frequency excitation, where the angle of external magnetic field is adjustable. The nonlinear dynamic equation with the identified nonlinear magnetic force is derived to describe the electromechanical interaction of variable inclination angle harvesters. The effect of excitation amplitude and frequency on dynamic behavior is proposed by using the phase trajectory and bifurcation diagram. The numerical analysis shows that a rotatable magnetically coupling energy harvesting system exhibits rich nonlinear characteristics with the change of external magnet inclination angle. The nonlinear route to and from large amplitude high energy motion can be clearly observed. It is demonstrated numerically and experimentally that lumped parameters equations with an identified polynomials for magnetic force could adequately describe the characteristics of nonlinear energy harvester. The rotating magnetically coupled energy harvester possesses the usable frequency bandwidth over a wide range of low frequency excitation by adjusting the angular orientation.


Author(s):  
Abdessattar Abdelkefi

There exist numerous low-frequency excitation sources, such as walking, breathing, and ocean waves, capable of providing viable amounts of mechanical energy to power many critical devices, including pacemakers, cell phones, MEMS devices, wireless sensors, and actuators. Harvesting significant energy levels from such sources can only be achieved through the design of devices capable of performing effective energy transfer mechanisms over low frequencies. In this chapter, two concepts of efficient low-frequency piezoelectric energy harvesters are presented, namely, variable-shaped piezoelectric energy harvesters and piezomagnetoelastic energy harvesters. Linear and nonlinear electromechanical models are developed and validated in this chapter. The results show that the quadratic shape can yield up to two times the energy harvested by a rectangular one. It is also demonstrated that depending on the available excitation frequency, an enhanced energy harvester can be tuned and optimized by changing the length of the piezoelectric material or by changing the distance between the two tip magnets.


Author(s):  
Xiaokun Ma ◽  
Hong Goo Yeo ◽  
Christopher D. Rahn ◽  
Susan Trolier-McKinstry

Piezoelectric energy harvesters typically perform poorly in the low frequency, low amplitude, and intermittent excitation environment of human movement. In this paper, a piezoelectric compliant mechanism (PCM) energy harvester is designed, modeled, and analyzed that consists of a PZT unimorph clamped at the base and attached to a compliant mechanism at the tip. The compliant mechanism has two flexures that amplify the tip displacement to produce large motion of a proof mass and a low frequency first mode with an efficient (nearly quadratic) shape. The compliant mechanism is fabricated as a separate, relatively rigid frame with flexure hinges, simplifying the fabrication process and surrounding and protecting the PZT unimorph. The bridge structure of the PCM also introduces an axial tensioning nonlinearity that self-limits the response to large amplitude impacts, improving the robustness of the device. Comparing the time domain performance based on realistic wrist acceleration data, the PCM produces 6 times more average power than a proof mass cantilever with the same unimorph area and natural frequency.


2013 ◽  
Vol 25 (12) ◽  
pp. 1429-1444 ◽  
Author(s):  
Abdessattar Abdelkefi ◽  
Nilma Barsallo ◽  
Lihua Tang ◽  
Yaowen Yang ◽  
Muhammad R Hajj

Author(s):  
Kuo-Shen Chen

Wireless sensor networks become increasingly important in modern life for structural health monitoring and other related applications. In these applications, due to their overall sensor populations and possible covered measurement areas, the replacement of batteries becomes a difficult and unrealistic task. As a result, energy harvesters to convert environment wasted vibration energy into electricity for powering those sensor nodes become important and many miniaturized device have been realized by using MEMS technology. In order to achieve optimal performance, the energy harvester must be operated at the resonance frequency. However, the vibration frequencies of environmental vibrations are usually much less than that of those miniaturizing energy harvesters and this fact could be a major barrier for energy harvesting performance. In this paper, a new piezoelectric energy scavenging concept is proposed and demonstrated to convert environmental vibrations into electricity. Unlike previous MEMS-based piezoelectric energy harvesters, which suffer from matching between environmental low frequency vibration and the much higher system natural frequency, this work proposes a novel beating design using polymer piezoelectric materials in collaborating with a beating mechanism. That is, by creating impact force via the low frequency vibration motion from the mechanism, it is possible to excite system natural frequency by the low frequency environmental vibrations and it is possible to operate the entire system at the natural frequency. This work contains details in presenting this idea, designing piezoelectric harvester systems with flexible PVDF elements, exploring their vibration characteristics, and energy accumulating strategies by using a capacitor with a full-bridged rectifiers or a boost conversion. By experimental characterization, the overall harvesting efficiency of the proposed design is much greater than that from the design without the beating mechanism. It indicates that the efficiency is significantly improved and the proposed translational design could potentially improve the future design approach for piezoelectric energy harvesters significantly. In summary, this preliminary study shows that it is a feasible scheme for the application of piezoelectric materials in harvesting electricity from environmental vibrations. Although this work is still in its initial phase, the results and conclusions of this work are still invaluable for guiding the development of high efficient piezoelectric harvesters in the future.


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