Magnetic Stoppers on Single Beam Piezoelectric Energy Harvesting

The single beam structure has been long used in piezoelectric energy harvesting to harvest the vibrations of the circumstances. One of the critical defects of the structure is its narrow band of operating frequency. Many propose mechanical stoppers, rigid or non-rigid, such as another beam, to create a non-linear broadband effect. Moreover, with a piecewise linear PEG (Piezoelectric Energy Generator), or a simple cantilever beam with one or two mechanical stoppers laid on its sides, the constant driven amplitude of the beam displacement can be enlarged by a perturbation. It is also proposed that the stoppers prevent the piezoelectric pad from cracking due to over deformation. However, from a long-term point of view, the impact of the beam on the stoppers can also cause faster fatigue of the beam body, not to mention the noise that will hinder its practical application which maybe apparatuses nearby human. Therefore, this paper proposes a magnetic pair to serve as the stoppers for piezoelectric beam, so as to perform similar eects of bandwidth enlargement and also the amplication using perturbation. With no actual contacts, the single beam can be well protected, but also eliminated from over bending by the magnets. By placing the magnets on a beam on each side of the main beam. The magnetic force, which is distance dependent, can provide a smoother feedback to the beam, giving a greater displacement in comparison to the mechanical stopper. Moreover, the characteristic of the beam output is altered so that there exists two peaking frequencies, depending on the design of the stopper beams.