A low-frequency rotational electromagnetic energy harvester using a magnetic plucking mechanism

In this paper a novel hybrid piezoelectric and electromagnetic energy harvester for civil engineering low-frequency sloshing environment is reported. The architecture, fabrication and characterization of the harvester are discussed. The hybrid energy harvester is composed of a permanent magnet, copper coil, and PVDF(polyvinylidene difluoride) piezoelectric film, and the upper U-tube device containing a cylindrical fluid barrier is connected to the foundation support plate by a hinge and spring. The two primary means of energy collection were through the vortex street, which alternately impacted the PVDF piezoelectric film through fluid shedding, and the electromotive force (EMF) induced by changes in the magnetic field position in the conducting coil. Experimentally, the maximum output power of the piezoelectric transformer of the hybrid energy harvester was 2.47 μW (circuit load 270 kΩ; liquid level height 80 mm); and the maximum output power of the electromagnetic generator was 2.72 μW (circuit load 470 kΩ; liquid level height 60 mm). The low-frequency sloshing energy collected by this energy harvester can drive microsensors for civil engineering monitoring.

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A Belleville-Spring Based Piezoelectric or Electromagnetic Energy Harvester

Volume 2: Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Bioinspired Smart Materials and Systems; Energy Harvesting ◽

10.1115/smasis2014-7424 ◽

2014 ◽

Author(s):

Davide Castagnetti

Keyword(s):

Energy Harvesting ◽

Power Output ◽

Experimental Validation ◽

Energy Harvester ◽

Elastic System ◽

Low Frequency ◽

Electromagnetic Energy ◽

Frequency Range ◽

Modal Response ◽

Force Displacement

Energy harvesting from kinetic ambient energy requires converters able to efficiently operate in the low frequency range. A limit of the solutions proposed in the literature, both electromagnetic and piezoelectric, is their operating frequency, which generally ranges from about 50 to 300 Hz. To overcome these limitations, this work proposes an innovative energy harvester exploiting two counteracting Belleville springs. Thanks to the peculiar height to thickness ratio of the springs a highly compliant elastic system is obtained, which can be used either for electromagnetic or piezoelectric harvesting. The harvester is modelled analytically and numerically both with regard to the force-displacement and to the modal response. The experimental validation of the harvester, highlights a noticeable power output but at a higher eigenfrequency than expected.

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An arc-shaped electromagnetic energy harvester for ultra-low frequency vibrations and swing motions

Active and Passive Smart Structures and Integrated Systems XIII ◽

10.1117/12.2513792 ◽

2019 ◽

Cited By ~ 1

Author(s):

Kangqi Fan ◽

Qinxue Tan ◽

Lihua Tang

Keyword(s):

Energy Harvester ◽

Low Frequency ◽

Electromagnetic Energy

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Two degree of freedom vibration based electromagnetic energy harvester for bridge health monitoring system

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x20959459 ◽

2020 ◽

pp. 1045389X2095945

Author(s):

Muhammad Masood Ahmad ◽

Farid Ullah Khan

Keyword(s):

Cantilever Beam ◽

Energy Harvester ◽

Low Frequency ◽

Open Circuit ◽

Electromagnetic Energy ◽

Degree Of Freedom ◽

Mode Shapes ◽

Fixed End ◽

Two Degree Of Freedom ◽

Maximum Voltage

This paper presents an electromagnetic energy harvester to extract low frequency and low acceleration vibration energy available in a bridge environment. The developed harvester is a multi-mode oscillator with dual electromagnetic transduction mechanisms. The harvester consists of two cantilever beams. The first cantilever beam is split into two equal pieces along its length and the second beam placed in between them coming back to the fixed end and attached at outer end to the first beam. This way instead of a long conventional cantilever beam a compact harvester is fabricated. Two magnets as proof masses are attached to each free end of the beam making it a two degree of freedom system (2-DOF). The magnets are positioned to oscillate inside hand wound coils during operation. An analytical model was developed and COMSOL multiphysics was used to simulate the mode shapes of the harvester. The mathematical model was simulated for open circuit voltage in MATLAB and showed closely matching results with the experimental values. The harvester is characterized in lab for its performance under sinusoidal vibrations at low frequency (3 Hz–15 Hz) and low acceleration (0.01–0.09 g) levels. The 2-DOF harvester has two resonant frequencies of 4.4 Hz and 5.5 Hz and a volume of 333 cm3. It produces maximum voltage of 0.6 V at first resonance on coil-1 and maximum voltage of 1.2 V on coil-2 at second resonance at 0.09 g. At acceleration of 0.09 g the harvester produced 2.51 mW at first resonant frequency and 10.7 mW at second resonance. Moreover, the AC output voltage of the harvester is rectified to DC voltage by a three-stage Cockcroft-Walton multiplier type circuit. The DC power output at 0.05 g was 0.939 mW at first resonance and 0.956 mW at second resonance while maximum voltages of 5.4 V on coil-1 and 4 V on coil-2 were produced.

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