Distributed parameter modelling and experimental validation of a piezoelectric bimorph cantilever energy harvester

Recent developments in low-power portable applications have accelerated research in the field of energy harvesting from ambient sources. Piezoelectric energy harvesters have remarkable potential to convert unused ambient vibrations into useful electrical energy that can subsequently provide power to low-power electronic systems for an infinite life span. This paper concerns the derivation of the mathematical model of a bimorph piezoelectric cantilever beam with distributed inertia, and its experimental validation. Previous research on such a component included a tip mass, which reduced the influence of the distributed inertia of the beam and restricted effective operation to low frequencies. The present research excludes the tip mass. The effects of backward electrical coupling on the mechanical properties of the harvester are investigated, particularly the dependence of the induced additional stiffness and damping on the electrical load and the piezoelectric properties. Both the model and the experimental results showed that the natural frequencies and the response amplitude of the harvester exhibited considerable shifts due to the electrical coupling, indicating change in stiffness and damping. The mechanical coupling effects on the electrical parameters (voltage, current and power output) are also analyzed. Copyright © 2009 by ASME.