Abstract
Harvesting electricity from low frequency vibration sources such as human motions using piezoelectric energy harvesters (PEH) is attracting the attention of many researchers in recent years. The energy harvested can potentially power portable electronic devices as well as some medical devices without the need of an external power source. For this purpose, the piezoelectric patch is often mechanically attached to a cantilever beam, such that the resonance frequency is predominantly governed by the cantilever beam. To increase the power generated from vibration sources with varying frequency, a multiresonant PEH (MRPEH) is often used. In this study, an attempt is made to enhance the performance of MRPEH with the use of a cantilever beam of optimised shape, i.e., a cantilever beam with two triangular branches. The performance is further enhanced through optimising the design of the proposed MRPEH to suit the frequency range of the targeted vibration source. A series of parametric studies were first carried out using finite-element analysis to provide in-depth understanding of the effect of each design parameters on the power output at a low frequency vibration. Selected outcomes were then experimentally verified. An optimised design was finally proposed. The results demonstrate that, with the use of a properly designed MRPEH, broadband energy harvesting is achievable and the efficiency of the PEH system can be significantly increased.
Highlights
Using renewable macroenergy harvesting systems like solar energy [1,2,3,4,5,6] or wind energy [7,8,9,10]has become popular over the past few decades
The frequency range of interest was swept through and the open circuit voltage generated by the multiresonant PEH (MRPEH) was measured
Results and Discussions swept through and the open circuit voltage generated by the MRPEH was measured
Summary
Using renewable macroenergy harvesting systems like solar energy [1,2,3,4,5,6] or wind energy [7,8,9,10]has become popular over the past few decades. The advancement of new methods and applications of wireless networks drives the demand on microenergy harvesting for continuous power supply [11]. Among these various renewable energy sources, such as biomass [12,13], heat [14] and vibration [15,16], vibration-based energy harvesting has attracted the interest of many researchers because of the ubiquity and availability of various vibration sources. Electrodynamic conversion methods are used to harvest energy from high-frequency vibration sources while piezoelectric materials are more suitable for converting mechanical energy to electrical energy for low-frequency excitations. Several other factors can affect the choice of harvesters, including size, weight, stability and total cost of the device to be powered
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