Modeling and Analysis of Bimorph Piezoelectromagnetic Energy Harvester

Abstract

Piezoelectric energy harvesting is one of the methods of obtaining energy from environment. It is often a cantilever beam with or without tip mass poled with piezoelectric material. The fixed end of cantilever beam is subjected to either base excitation or translation as occurring from an environmental source such as automobile or vibrating engine. The piezoelectric energy harvester generates maximum energy when it is excited at resonance frequency and the little variation below or above the resonance frequency will drastically reduce the power output. In this line, present work studies a broadband nonlinear piezoelectric energy harvester driven by periodic and random oscillations. The simulated response to the base excitation is illustrated in terms of harvested power. By introducing magnetic force, we can broaden the frequency zone so as to capture more energy even the beam do not vibrate close to source frequency. A magnetic tip is included at the free end of the cantilever beam and is excited by two permanent magnets fixed on either sides laterally. The symmetric bimorph cantilever beam piezoelectric energy harvester with magnetic tip is modeled as Single-degree of freedom lumped parameter system. The time domain history and frequency response diagrams for the cantilever displacement, voltage and power at the constant load resistance gives a stability picture as well as the amount of energy harvested. The effect of various parameters of energy harvester system on induced voltage and output power is studied. The distributed parameter model is formulated by using Euler-Bernoulli beam theory and Galerkin’s approximation technique. The finite element modeling equations are presented with piezoelectric coupling terms. Novelty in the work include; (i) adding a magnetic force in the system to make it as broadband harvester (ii) validation of approximation solutions with spring-mass modeling.