Nonlinear Dynamic Characteristics of Variable Inclination Magnetically Coupled Piezoelectric Energy Harvesters

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Junyi Cao ◽  
Shengxi Zhou ◽  
Daniel J. Inman ◽  
Jing Lin

This paper investigates the nonlinear dynamic characteristics of a magnetically coupled piezoelectric energy harvester under low frequency excitation where the angle of the 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, power spectrum, and bifurcation diagram. The numerical analysis shows that a rotating magnetically coupled 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):  
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.


2019 ◽  
Vol 97 (4) ◽  
pp. 2371-2397 ◽  
Author(s):  
Guangqing Wang ◽  
Wei-Hsin Liao ◽  
Zexiang Zhao ◽  
Jiangping Tan ◽  
Sujuan Cui ◽  
...  

Author(s):  
Ming Hui Yao ◽  
Wei Xia ◽  
Wei Zhang ◽  
Jian Yu Jiao

This paper presents a special piezoelectric energy harvester system which is obtained by separating the end of the upper piezoelectric layer of the traditional piezoelectric cantilever beam from its basic layer. A mass I is located at the end of the separated upper piezoelectric layer (SUPL), a mass II and a permanent magnet I are located at the end of the separated lower piezoelectric beam (SLPB) and a permanent magnet II is added in the opposite position of the permanent magnet I and they face each other with same polarities. A nonlinear magnetic force which can broaden the frequency bandwidth of the system is generated mutually on the two permanent magnets. Studies find that this special piezoelectric energy harvester has extremely high energy capture efficiency. In order to further explore the reason of high efficiency, experimental research on its dynamic behavior is carried out. The experimental results show that the vibrations of the SUPL and the SLPB are relatively simple. The dynamic behaviors of the SUPL, the SLPB and the unseparated part are different. The unseparated part of the piezoelectric shows relatively complex nonlinear phenomenon due to the interaction of nonlinear magnetic force and the collision. With the increase of the external excitation frequency, period doubling motion and almost periodic motion appear alternately.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5077
Author(s):  
David Omooria Masara ◽  
Hassan El Gamal ◽  
Ossama Mokhiamar

This paper presents a new way to design a broadband harvester for harvesting high energy over a low-frequency range of 10–15 Hz. The design comprises a cantilever beam with two parallel grooves to form three dissimilar length parallel branches, each with an unequal concentrated tip mass. The piezoelectric material covers the whole length on both sides of the beam to form a bimorph. Appropriate geometry and mass magnitudes are obtained by a parametric study using the Finite Element Method. The design was simulated in COMSOL Multiphysics to study its response. The first three bending modes were utilized in energy harvesting, resulting in three power peaks at their respective fundamental frequencies. The adequate load resistance determined was 5.62 kΩ, at which maximum power can be harvested. The proposed harvester was compared to two other harvesters presented in the literature for validation: First, an optimized conventional harvester while the proposed harvester is operating at adequate load resistance. Second, a multimodal harvester, while the proposed harvester is operating at a 10 kΩ load. The suggested harvester proved to be more efficient by harvesting sufficiently higher broadband energy and is applicable in a wide range of vibration environments because of its adaptability in design.


Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 203
Author(s):  
Xiaohua Huang ◽  
Cheng Zhang ◽  
Keren Dai

Using the piezoelectric effect to harvest energy from surrounding vibrations is a promising alternative solution for powering small electronic devices such as wireless sensors and portable devices. A conventional piezoelectric energy harvester (PEH) can only efficiently collect energy within a small range around the resonance frequency. To realize broadband vibration energy harvesting, the idea of multiple-degrees-of-freedom (DOF) PEH to realize multiple resonant frequencies within a certain range has been recently proposed and some preliminary research has validated its feasibility. Therefore, this paper proposed a multi-DOF wideband PEH based on the frequency interval shortening mechanism to realize five resonance frequencies close enough to each other. The PEH consists of five tip masses, two U-shaped cantilever beams and a straight beam, and tuning of the resonance frequencies is realized by specific parameter design. The electrical characteristics of the PEH are analyzed by simulation and experiment, validating that the PEH can effectively expand the operating bandwidth and collect vibration energy in the low frequency. Experimental results show that the PEH has five low-frequency resonant frequencies, which are 13, 15, 18, 21 and 24 Hz; under the action of 0.5 g acceleration, the maximum output power is 52.2, 49.4, 61.3, 39.2 and 32.1 μW, respectively. In view of the difference between the simulation and the experimental results, this paper conducted an error analysis and revealed that the material parameters and parasitic capacitance are important factors that affect the simulation results. Based on the analysis, the simulation is improved for better agreement with experiments.


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