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Research Papers

Increasing the Performance of a Rotary Piezoelectric Frequency Up-Converting Energy Harvester Under Weak Excitations

[+] Author and Article Information
Reza Ramezanpour

Department of Mechanical Engineering,
Isfahan University of Technology,
Isfahan 84156-83111, Iran
e-mail: r.ramezanpour.k@me.iut.ac.ir

Hassan Nahvi

Department of Mechanical Engineering,
Isfahan University of Technology,
Isfahan 84156-83111, Iran
e-mail: hnahvi@cc.iut.ac.ir

Saeed Ziaei-Rad

Department of Mechanical Engineering,
Isfahan University of Technology,
Isfahan 84156-83111, Iran
e-mail: szrad@cc.iut.ac.ir

1Corresponding author.

Contributed by the Technical Committee on Vibration and Sound of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received January 18, 2016; final manuscript received September 28, 2016; published online December 7, 2016. Assoc. Editor: Lei Zuo.

J. Vib. Acoust 139(1), 011016 (Dec 07, 2016) (10 pages) Paper No: VIB-16-1032; doi: 10.1115/1.4035029 History: Received January 18, 2016; Revised September 28, 2016

In common rotary piezoelectric (PZT) frequency up-converting energy harvesters, impact or nonimpact frequency up-conversion technologies are used. For low separation distances between the magnets in nonimpact cases, when weak excitation is applied, depending on some parameters such as separation distance between the magnets, eccentric proof mass may be unable to overcome the magnetic potential between the magnets, and thus, the extracted power of the harvester lowers. To increase the harvester power output, the use of an additional pair of magnets, called the assisting part, is proposed in this paper. For different harmonic excitations, the generated powers of the harvester with and without assisting part have been compared to each other. It is found that by appropriately adjusting the separation distance, the use of such part can increase the generated power in most cases. Using a real-world multifrequency multi-amplitude excitation, the ability of the proposed idea to increase the extracted power is investigated. It is found that the maximum generated power of the device can effectively increase to more than two times. In order to check the accuracy of the applied mathematical modeling, some experiments have been conducted.

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References

Figures

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Fig. 1

Schematic diagram of a PZT frequency up-converting energy harvester; the central bar and the clamp support are fixed to base plate, while the eccentric proof mass is free to rotate around the central bar

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Fig. 2

Schematic diagram of the harvester consisting of an assisting part

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Fig. 3

Schematic diagram of the harvester shown in Fig. 2 without assisting part

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Fig. 4

Parameters used for modeling nonlinear magnetic interaction among the two rotating magnets and the tip-magnet, and among the two rotating magnets and the fixed one; separation distances ZR1 and ZR2 are shown in the figure

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Fig. 5

Variation of the moment of magnetic force versus time for various separation distances of the assisting part (ZR1); the constant angular velocity of the pendulum and the separation distance ZR2 are kept constant as π rad/s and 20 mm, respectively

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Fig. 6

The generated power of the harvester versus excitation frequencies for various separation distances (shown at the top of each column) and amplitude of excitations: A=0.1 g, A=0.25 g, A=0.5 g, A=1 g, and A=2 g, respectively; continuous lines are drawn for the harvester with assisting part and dashed lines are drawn for the harvester without assisting part; ZR2=25 mm

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Fig. 7

The generated power of the harvester versus excitation frequencies for various separation distances (shown at the top of each column) and amplitude of excitations: A=0.1 g, A=0.25 g, A=0.5 g, A=1 g, and A=2 g, respectively; continuous lines are drawn for the harvester with assisting part and dashed lines are drawn for the harvester without assisting part; ZR2=20 mm

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Fig. 8

The generated power of the harvester versus excitation frequencies for various separation distances (the title of each column) and amplitude of excitations: first, second, third, fourth, and fifth rows are depicted for A=0.1 g, A=0.25 g, A=0.5 g, A=1 g, and A=2 g, respectively; continuous lines are drawn for the harvester with assisting part, while dashed lines are drawn for the harvester without assisting part; ZR2=15 mm

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Fig. 9

(a) General scheme of the experimental apparatus and (b) details of the fabricated energy harvester including assisting part (the ηo angles are shown on the glued paper)

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Fig. 10

The RMS of voltage for the harvester with (continues lines) and without (dashed–dotted lines) assisting part, measured for different separation distances of the assisting part; the angles from which the pendulum is dropped are presented as legend; ZR2=19.4 mm

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Fig. 11

In second series of tests, the ψ angle slowly increased so that at a particular angle (ψo), which here is called the leaving angle, the pendulum leaves the beam. The measured ψo angles are presented in Fig. 12.

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Fig. 12

The angles at which the pendulum is able to overcome the repulsive or attractive potential field of the piezoelectric tip magnet versus the separation distance of the assisting part; drawn for separation distance of ZR2=19.4 mm

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Fig. 13

Variation of the RMS of voltage versus ZR1 obtained from theoretical model and for the harvester with (continuous lines) and without (dashed–dotted lines) assisting part; the angles from which the pendulum is dropped are presented as legend; (a) ZR2=20 mm and (b) ZR2=25 mm

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Fig. 14

The leaving angle obtained by theoretical model versus ZR1; ZR2=25 mm

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Fig. 15

The generated power of the harvester with (continuous line) and without (dashed line) assisting part for separation distances of (a) ZR2=15 mm and (b) ZR2=25 mm; the harvester is excited by a real-world acceleration signal obtained from the Energy Harvesting Network Dataset Repository (see Ref. [28])

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