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.

Orbit Jumps of Monostable Energy Harvesters by a Bidirectional Energy Conversion Circuit

2019 ◽  
Author(s):  
Jiahua Wang ◽  
Bao Zhao ◽  
Junrui Liang ◽  
Wei-Hsin Liao
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Vibration Amplitude ◽  
Energy Harvester ◽  
High Energy ◽  
Wide Frequency Range ◽  
Energy Harvesters ◽  
Novel Approach ◽  
Switch Control ◽  
Nonlinear Energy

Abstract Nonlinear energy harvesters have been widely studied in the last decade. Their broad bandwidth and relatively high power output contribute to energy harvesting applications. However, the coexisting multiple orbits brought by the nonlinearity weaken the performance of nonlinear energy harvesters. This paper proposes to achieve orbit jumps of monostable energy harvesters by a bidirectional energy conversion circuit. Changing the switch control sequence in the bidirectional energy conversion circuit facilitates it with both the energy harvesting and vibration exciting functions. Thus, a nonlinear energy harvester in connection with the circuit can harness ambient energy as well as excite itself, through energy harvesting and vibration exciting modes separately. Based on the concept of vibration exciting, the energy saved in the storage is used to stimulate the piezoelectric transducer for a larger vibration amplitude, which enables orbit jumps. The working mechanism of the circuit is introduced. Experimental setup of a monostable energy harvester has been developed to validate the proposed method. The monostable system can be stimulated to high-energy orbit from a small vibration amplitude by the vibration exciting mode of the circuit. It is also revealed that the method can achieve orbit jumps in a wide frequency range within the hysteresis area. Evaluations on energy consumption and energy gain show that the sacrificed energy can be quickly recovered. A novel approach for orbit jumps of monostable energy harvesters is performed so as to open new opportunities for monostable energy harvesters.

Current progress and performance improvement of Pt/C catalysts for fuel cells

2020 ◽  
Vol 8 (46) ◽  
pp. 24284-24306
Author(s):  
Xuefeng Ren ◽  
Yiran Wang ◽  
Anmin Liu ◽  
Zhihong Zhang ◽  
Qianyuan Lv ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Energy Conversion ◽  
Performance Improvement ◽  
Electric Energy ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Carnot Cycle ◽  
High Energy Conversion Efficiency ◽  
And Performance

Fuel cell is an electrochemical device, which can directly convert the chemical energy of fuel into electric energy, without heat process, not limited by Carnot cycle, high energy conversion efficiency, no noise and pollution.

Enhanced frequency synchronization for concurrent aeroelastic and base vibratory energy harvesting using a softening nonlinear galloping energy harvester

2021 ◽  
pp. 1045389X2110263
Author(s):  
Shun Chen ◽  
David Eager ◽  
Liya Zhao
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Poor Performance ◽  
Effective Bandwidth ◽  
Frequency Synchronization ◽  
Periodic Oscillations ◽  
Energy Harvesters ◽  
Paper Form ◽  
Excited Oscillation

This paper proposes a softening nonlinear aeroelastic galloping energy harvester for enhanced energy harvesting from concurrent wind flow and base vibration. Traditional linear aeroelastic energy harvesters have poor performance with quasi-periodic oscillations when the base vibration frequency deviates from the aeroelastic frequency. The softening nonlinearity in the proposed harvester alters the self-excited galloping frequency and simultaneously extends the large-amplitude base-excited oscillation to a wider frequency range, achieving frequency synchronization over a remarkably broadened bandwidth with periodic oscillations for efficient energy conversion from dual sources. A fully coupled aero-electro-mechanical model is built and validated with measurements on a devised prototype. At a wind speed of 5.5 m/s and base acceleration of 0.1 g, the proposed harvester improves the performance by widening the effective bandwidth by 300% compared to the linear counterpart without sacrificing the voltage level. The influences of nonlinearity configuration, excitation magnitude, and electromechanical coupling strength on the mechanical and electrical behavior are examined. The results of this paper form a baseline for future efficiency enhancement of energy harvesting from concurrent wind and base vibration utilizing monostable stiffness nonlinearities.

Direct-Write Piezoelectric Polymeric Nanogenerator with High Energy Conversion Efficiency

Nano Letters ◽  
2010 ◽  
Vol 10 (2) ◽  
pp. 726-731 ◽  
Author(s):  
Chieh Chang ◽  
Van H. Tran ◽  
Junbo Wang ◽  
Yiin-Kuen Fuh ◽  
Liwei Lin
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Direct Write ◽  
High Energy Conversion Efficiency

A Grid Connected Flyback Inverter with a DC Active Filter for Photovoltaic Cells

2015 ◽  
Vol 781 ◽  
pp. 406-409
Author(s):  
Dome Sulong ◽  
Chuttchaval Jeraputra
Keyword(s):  
Current Mode ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Active Filter ◽  
Full Wave ◽  
Pv Module ◽  
High Energy Conversion Efficiency ◽  
Sinusoidal Current ◽  
Dc Current ◽  
And Control

This paper presents the design and control of a grid-connected flyback inverter with a DC active filter for photovoltaic (PV) cells. The proposed topology consists of a flyback DC-AC inverter and a DC active filter that can operate independently. The flyback inverter, controlled in digital peak current mode, regulates the full-wave rectified sinusoidal current later, which is alternately inverted and injected into the grid. The DC active filter regulates the smooth current/power drawn from a PV module by using cascaded proportional-integral (PI) controllers. Analysis, design and control of the proposed topology are presented. A 100W/220V/50Hz prototype is developed and tested. The experimental results show that the proposed flyback inverter with a DC active filter is capable of regulating a sinusoidal current fed into the grid, actively filtering the DC current/power and achieving reasonably high energy conversion efficiency.

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