Increasing the power of piezoelectric energy harvesters by magnetic stiffening

Abstract

A piezoelectric cantilever beam with a tip mass at its free end is a common energy harvester configuration. This article introduces a new principle of designing such a harvester that increases the generated power without changing the resonance frequency of the harvester: the attraction force between two permanent magnets is used to add stiffness to the system. This magnetic stiffening counters the effect of the tip mass on the efficient operation frequency. Five set-ups incorporating piezoelectric bimorph cantilevers of the same type in different mechanical configurations are compared theoretically and experimentally to investigate the feasibility of this principle: theoretical and experimental results show that magnetically stiffened harvesters have important advantages over conventional set-ups with and without tip mass. They generate more power while only slightly increasing the deflection in the piezoelectric harvester and they can be tuned across a wide range of excitation frequencies.

Nonlinear Dynamics and Power Generation on a New Bistable Piezoelectric-Electromagnetic Energy Harvester

“…Based on the practical working condition of the structure and theoretical and numerical studies given by Arrieta et al [9,10], it is known that vibrations of the first-order mode for the beam play an important role during vibration. e power 6 Complexity generation of the bistable piezoelectric-electromagnetic combined structure mainly depends on vibration of the firstorder mode in the beam.…”

“…e bistable cantilevered structure enhanced the harvesting efficiency of the system. Al-Ashtari et al [10] introduced a new design of the energy harvester, which improved the output power without changing the resonance frequency of the structure. e stiffness of the structure was added by the attractive force between two permanent magnets.…”

Design, Tuning and In-Field Validation of Energy Harvesters for Railway Bridges

“…The simulations showed the self-tuning system increased the output power around 26 times compared to a device with a fixed tuning frequency. Al-Ashtari et al [18] modified the stiffness of the harvester using two permanent magnets to improve performance in a wide range of excitation frequencies. Furthermore, Karadag et al [19] proposed a self-tuning method with a movable mass attached to the beam substructure.…”

Using an elastic magnifier to increase power output and performance of heart-beat harvesters

“…Karami et al [11] developed a unified approximation method for linear, monostable, and bistable structures which analyzed the effects of electro-mechanical coupling on each system caused by variations in damping and excitation frequency. Many other researchers have contributed to the development, understanding, and investigation of nonlinear and bistable piezoelectric energy harvesters [12][13][14][15][16][17] including work in MEMS [18] and applications for mobile devices [19].…”