KEYWORDS: Energy harvesting, Magnetism, Fermium, Frequency modulation, Electromagnetism, Copper, Double positive medium, Resistance, Energy efficiency, Complex systems
This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation (HDL) mechanism based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume figure of merit (FoMv). The HDL mechanism comprises of three permanent magnets and two diamagnetic plates. Two of the magnets, aka lifting magnets, are placed co-axially at a distance such that each attract a centrally located magnet, aka floating magnet, to balance its weight. This floating magnet is flanked closely by two diamagnetic plates which stabilize the levitation in the axial direction. The influence of the geometry of the floating magnet, the lifting magnet and the diamagnetic plate are parametrically studied to quantify their effects on the size, stability of the levitation mechanism and the resonant frequency of the floating magnet. For vibration energy harvesting using the HDL mechanism, a coil geometry and eddy current damping are critically discussed. Based on the analysis, an efficient experimental system is setup which showed a softening frequency response with an average system efficiency of 25.8% and a FoMv of 0.23% when excited at a root mean square acceleration of 0.0546 m/s2 and at frequency of 1.9 Hz.
This article investigates a horizontal diamagnetic levitation (HDL) system for vibration energy harvesting. In this configuration, two large magnets, alias lifting magnets, are arranged co-axially at a distance such that in between them a magnet, alias floating magnet, is passively levitated at a laterally offset equilibrium position. The levitation is stabilized in the horizontal direction by two diamagnetic plates made of pyrolytic graphite placed on each side of the floating magnet. This HDL configuration permits large amplitude vibration of the floating magnet and exploits the ability to tailor the geometry to meet specific applications due to its frequency tuning capability. Theoretical modeling techniques are discussed followed by an experimental setup to validate it. At an input root mean square (RMS) acceleration of 0.0434 m/s2 (0.0044 grms) and at a resonant frequency of 1.2 Hz, the prototype generated a RMS power of 3.6 μW with an average system efficiency of 1.93%. Followed by the validation, parametric studies on the geometry of the components are undertaken to show that with the optimized parameters the efficiency can be further enhanced.
KEYWORDS: Magnetism, Wind energy, Copper, Energy harvesting, Sensors, Electromagnetism, Resistance, Mathematical modeling, Magnetic sensors, Very large scale integration
In this paper a novel electromagnetic vibration type energy harvester which uses a diamagnetic levitation system is
conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite
between which a cylindrical magnet levitates passively. Two archimedean spiral coils are placed in grooves which are
engraved in the pyrolytic graphite plates, used to convert the mechanical energy into electrical energy efficiently. The
geometric configurations of coils are selected based on the field distribution of the magnet to enhance the efficiency of
the harvester. A thorough theoretical analysis is done to compare with the experiment results. At an input power of
103.45 μW and at a frequency of 2.7 Hz, the harvester generated a power of 0.744 μW at an efficiency of 0.72 %. Both
theoretical and experimental results show that this new energy harvesting system is efficient and can capture low
frequency broadband spectra.
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