Increased power output of an electromagnetic vibration energy harvester through anti-phase resonance. (1st February 2019)

• Record Type: Journal Article
• Authors: Foong, Faruq Muhammad; Thein, Chung Ket; Ooi, Beng Lee; Yurchenko, Daniil
• Is Part Of: Mechanical systems and signal processing. Volume 116(2019)
• Page Start: 129
• Page End: 145
• Publication Date: 2019-02-01
• Subjects: Vibration energy harvesting -- Out-of-phase -- Resonance -- Cantilever beam -- Power; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2018.06.012
• Languages: English
• ISSNs: 0888-3270

Abstract

Graphical abstract: Highlights: Electromagnetic harvesters power increases with increase in relative velocity. Proposed method achieved anti-phase motion between coil and magnets at resonance. Proposed design recorded an increase in bandwidth and power density. Maximum phase difference and power produced when natural frequencies are equal. Base on material, harvester gain can increase when effective mass of beam increase. Abstract: This paper proposes a novel method to increase the power output of a cantilever beam-based electromagnetic vibration energy harvester through anti-phase resonance. A new cantilever beam design is presented to achieve this. By introducing an anti-phase motion between the coil and the magnets at resonance under the same base excitation input, the relative velocity of the coil cutting through the magnetic field is significantly increased and hence its power output. An experiment is performed to compare the proposed method with the conventional method where either the coil or the magnet is fixed onto the vibrating base. Under a base acceleration level of 0.10 g and a natural frequency of 17.24 Hz, results shows a 185% increase in power for the proposed method when compared with the conventional method with a recorded maximum power of 7.4 mW at resonance. The power produced by this method is proven to be higher than the sum of power produced by two individual conventional harvesters under the same velocities. In addition, a 22% increase in frequency bandwidth is also recorded by the proposed method. In terms of the power density, the proposed method indicates a 38% increase when compared with the conventional harvester. Results also show a drastic reduction in the maximum power output and phase difference when the natural frequencies of the coil and the magnets differ by only 1.5%, hence defining the importance of frequency matching. Further analysis indicates that a glass fiber cantilever beam showed a higher decrease in electromagnetic damping as compared to the increase in mechanical damping when small bulk masses were added onto the beam, hence increasing its overall gain.