scholarly journals Stabilisation of the high-energy orbit for a non-linear energy harvester with variable damping

2015 ◽  
Vol 230 (12) ◽  
pp. 2003-2012 ◽  
Author(s):  
Dongxu Su ◽  
Rencheng Zheng ◽  
Kimihiko Nakano ◽  
Matthew P Cartmell
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
High Energy ◽  
Low Energy ◽  
Additional Energy ◽  
Non Linear ◽  
In Series ◽  
Improved Performance ◽  
Non Linear Oscillator ◽  
Energy Orbit

The non-linearity of a hardening-type oscillator provides a wider bandwidth and a higher energy harvesting capability under harmonic excitations. Also, both low- and high-energy responses can coexist for the same parameter combinations at relatively high excitation levels. However, if the oscillator’s response happens to coincide with the low-energy orbit then the improved performance achieved by the non-linear oscillator over that of its linear counterpart, could be impaired. This is therefore the main motivation for stabilisation of the high-energy orbit. In the present work, a schematic harvester design is considered consisting of a mass supported by two linear springs connected in series, each with a parallel damper, and a third-order non-linear spring. The equivalent linear stiffness and damping coefficients of the oscillator are derived through variation of the damper element. From this adjustment the variation of the equivalent stiffness generates a corresponding shift in the frequency–amplitude response curve, and this triggers a jump from the low-energy orbit to stabilise the high-energy orbit. This approach has been seen to require little additional energy supply for the adjustment and stabilisation, compared with that needed for direct stiffness tuning by mechanical means. Overall energy saving is of particular importance for energy harvesting applications. Subsequent results from simulation and experimentation confirm that the proposed method can be used to trigger a jump to the desirable state, thereby introducing a beneficial addition to the performance of the non-linear hardening-type energy harvester that improves overall efficiency and broadens the bandwidth.

Investigations of a Stiffness Tunable Nonlinear Vibrational Energy Harvester

2014 ◽  
Vol 14 (08) ◽  
pp. 1440023 ◽  
Author(s):  
Dongxu Su ◽  
Kimihiko Nakano ◽  
Rencheng Zheng ◽  
Matthew P. Cartmell
Keyword(s):  
Energy Harvesting ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Duffing Oscillator ◽  
Experimental Tests ◽  
High Energy ◽  
Practical Implementation ◽  
Energy Harvesting Devices ◽  
Energy Orbit

The recent potential benefit of nonlinearity has been applying in order to improve the effectiveness of energy harvesting devices. For instance, at relatively high excitation levels, both low and high-energy responses can coexist for the same parameter combinations in a hardening type Duffing oscillator, and this provides a wider bandwidth and a higher energy harvesting effectiveness under periodic excitations. However, frequency or amplitude sweeps of the excitation must be used in order to reach a desirable high-energy orbit, and this gives a limitation on practical implementation. This paper presents a stiffness tunable nonlinear vibrational energy harvester which contains a moving magnetic end mass attached to a cantilever beam, whose nonlinearity emerges from the interaction forces with two neighboring permanent magnets facing with opposing poles. The motivating hypothesis has been that the jump from the low-energy orbit to the high-energy orbit can be triggered by tuning the stiffness of the system without changing the frequency or the amplitude of the excitation. Theoretical investigations show a methodology for tuning stiffness, and experimental tests have validated that the proposed method can be used to trigger a jump to the desirable state, and hereby this can broaden the bandwidth of the energy harvester.

Flexoelectric Energy Harvesting Using Circular Thin Membranes

2020 ◽  
Vol 87 (9) ◽  
Author(s):  
Zhaoqi Li ◽  
Qian Deng ◽  
Shengping Shen
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Circular Membrane ◽  
Governing Equations ◽  
Energy Harvesters ◽  
Thin Membranes ◽  
High Energy Conversion Efficiency ◽  
Working Frequency

Abstract In this work, we propose a circular membrane-based flexoelectric energy harvester. Different from previously reported nanobeams based flexoelectric energy harvesters, for the flexoelectric membrane, the polarization direction around its center is opposite in sign to that far away from the center. To avoid the cancelation of the electric output, electrodes coated to upper and lower surfaces of the flexoelectric membrane are respectively divided into two parts according to the sign of bending curvatures. Based on Hamilton’s principle and Ohm’s law, we obtain governing equations for the circular membrane-based flexoelectric energy harvester. A generalized assumed-modes method is employed for solving the system, so that the performance of the flexoelectric energy harvester can be studied in detail. We analyze the effects of the thickness h, radius r0, and their ratio on the energy harvesting performance. Specifically, we show that, by selecting appropriate h and r0, it is possible to design an energy harvester with both high energy conversion efficiency and low working frequency. At last, through numerical simulations, we further study the optimization ratio for which the electrodes should be divided.

scholarly journals Efficient Broadband Vibration Energy Harvesting Using Multiple Piezoelectric Bimorphs

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Hamed Farokhi ◽  
Alireza Gholipour ◽  
Mergen H. Ghayesh
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
Nonlinear Models ◽  
Low Frequency ◽  
Load Resistance ◽  
Numerical Continuation ◽  
Vibration Energy Harvesting ◽  
Optimum Load ◽  
In Series ◽  
Piezoelectric Bimorphs

Abstract This paper presents complete nonlinear electromechanical models for energy harvesting devices consisting of multiple piezoelectric bimorphs (PBs) connected in parallel and series, for the first time. The proposed model is verified against available experimental results for a specific case. The piezoelectric and beam constitutive equations and different circuit equations are utilized to derive the complete nonlinear models for series and parallel connections of the PBs as well as those of piezoelectric layers in each bimorph, i.e., four nonlinear models in total. A multi-modal Galerkin approach is used to discretize these nonlinear electromechanical models. The resultant high-dimensional set of equations is solved utilizing a highly optimized and efficient numerical continuation code. Examining the system behavior shows that the optimum load resistance for an energy harvester array of 4 PBs connected in parallel is almost 4% of that for the case with PBs connected in series. It is shown an energy harvesting array of 8 PBs could reach a bandwidth of 14 Hz in low frequency range, i.e., 20–34 Hz. Compared with an energy harvester with 1 PB, it is shown that the bandwidth can be increased by more than 300% using 4 PBs and by more than 500% using 8 PBs. Additionally, the drawbacks of a multi-PB energy harvesting device are identified and design enhancements are proposed to improve the efficiency of the device.

scholarly journals Stabilising high energy orbit oscillations by the utilisation of centrifugal effects for rotating-tyre-induced energy harvesting

2018 ◽  
Vol 112 (14) ◽  
pp. 143901 ◽  
Author(s):  
Yunshun Zhang ◽  
Rencheng Zheng ◽  
Kimihiko Nakano ◽  
Matthew P. Cartmell
Keyword(s):  
Energy Harvesting ◽  
High Energy ◽  
Energy Orbit

scholarly journals Combining sustainable stochastic resonance with high-energy orbit oscillation to broaden rotational bandwidth of energy harvesting from tire

AIP Advances ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 015011
Author(s):  
Yunshun Zhang ◽  
Yingfeng Cai ◽  
Xiaopeng Teng ◽  
Rencheng Zheng ◽  
Kimihiko Nakano
Keyword(s):  
Energy Harvesting ◽  
Stochastic Resonance ◽  
High Energy ◽  
Energy Orbit

Self-Powered Synchronized Switching Interfacing Circuits for Micro-Piezoelectric Energy Harvesters

2013 ◽  
Author(s):  
Ya Shan Shih ◽  
Shun Chiu Lin ◽  
Mickaël Lallart ◽  
Wen Jong Wu
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
Steel Substrate ◽  
Mechanical Quality Factor ◽  
Enhancement Effect ◽  
Power Gain ◽  
External Energy ◽  
Piezoelectric Energy ◽  
Non Linear ◽  
Self Powered

In this work, we have combined a micro-piezoelectric energy harvester with a dedicated interfacing circuit using the non-linear switch harvesting techniques based on the concept of SSH (synchronized switch harvesting). We especially focused on the power enhancement effect of the switching technique on micro-power generators. The micro-piezoelectric energy harvester that was used in this work is based on a stainless steel substrate, which largely improved the power output capability of the device. The resonant frequency of the energy harvesting device is 117 Hz, giving a voltage output of 3.85 V under the acceleration of 0.05 g. The overall size of the harvesting device is merely 8*6*0.5 mm3, including the proof mass. In order to further enhance the power generation abilities of the micro-generator, non-linear electrical interface circuits have also been designed and tested on two devices. According to the value of the figure of merit given by the product of the squared coupling coefficient k2 by the mechanical quality factor QM, a significant power gain compared to standard energy harvesting interface up to 3.13 has been tested for the device featuring a k2QM value of 0.17. A gain of 1.85 for a device with a k2QM value of 0.42 was also found. All of which were in good agreement with theoretical predictions. Furthermore, in order to be as close as possible to the realistic implementation of the micro-generators, the above mentioned nonlinear interface circuit were implemented in a self-powered design (i.e., without requiring an external energy source) using a very small part of the energy available generated from the piezoelectric energy harvester. Using the self powered technique, the overall system was available to provide 91.4 μW, with accelerations around 0.75 g, under the condition of k2QM = 0.72, and the power gain of 2.03.

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