Abstract
Abstract This paper presents complete nonlinear electromechanical models for energy harvesting devices consisting of multiple piezoelectric bimorphs (PBs) connected in parallel and series, for the first time. The proposed model is verified against available experimental results for a specific case. The piezoelectric and beam constitutive equations and different circuit equations are utilized to derive the complete nonlinear models for series and parallel connections of the PBs as well as those of piezoelectric layers in each bimorph, i.e., four nonlinear models in total. A multi-modal Galerkin approach is used to discretize these nonlinear electromechanical models. The resultant high-dimensional set of equations is solved utilizing a highly optimized and efficient numerical continuation code. Examining the system behavior shows that the optimum load resistance for an energy harvester array of 4 PBs connected in parallel is almost 4% of that for the case with PBs connected in series. It is shown an energy harvesting array of 8 PBs could reach a bandwidth of 14 Hz in low frequency range, i.e., 20–34 Hz. Compared with an energy harvester with 1 PB, it is shown that the bandwidth can be increased by more than 300% using 4 PBs and by more than 500% using 8 PBs. Additionally, the drawbacks of a multi-PB energy harvesting device are identified and design enhancements are proposed to improve the efficiency of the device.
Highlights
Environmental vibration is a source of energy which can be used to power small wireless electronics and sensors, such as MEMS devices [1,2,3,4,5,6,7,8,9,10,11], to make them powerautonomous and to remove the need for a battery for their continuous operation [12,13,14]
Zhao and Yang [27] introduced a mechanical constraint to an energy harvester operating on wind flow and base vibration. This investigation presents, as the first endeavour, complete nonlinear models for multi-modal electro/mechanical analysis of energy harvester devices consisting of multiple piezoelectric bimorphs (PBs) connected in parallel or series
The general nonlinear coupled equations for the jth piezoelectric bimorph are utilised to derive the complete nonlinear model for an array of PBs connected in parallel, i.e. the configurations shown in Figs. 2(c) and 2(d)
Summary
Environmental vibration is a source of energy which can be used to power small wireless electronics and sensors, such as MEMS devices [1,2,3,4,5,6,7,8,9,10,11], to make them powerautonomous and to remove the need for a battery for their continuous operation [12,13,14]. Xue et al [19] developed an analytical solution to the response of a multi-bimorph energy harvesting device connected in parallel and series through use of a single-mode linear model of the piezoelectric bimorph. Experimental investigations were performed by Mann and Sims [20] on a magnetic energy harvesting device; they conducted theoretical analysis as well utilising a single-mode duffing-type model. Influences of an added tip mass on the performance of an energy harvester was examined by Kim et al [22], who employed a single-mode linear model for theoretical calculations. Zhao and Yang [27] introduced a mechanical constraint to an energy harvester operating on wind flow and base vibration This investigation presents, as the first endeavour, complete nonlinear models for multi-modal electro/mechanical analysis of energy harvester devices consisting of multiple piezoelectric bimorphs (PBs) connected in parallel or series. Through conducting a detailed parametric analysis on the proposed nonlinear model, design enhancements are proposed to improve the efficiency of multi-PB energy harvesting devices
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