Numerical and experimental study of bistable piezoelectric energy harvester. (MS)

Abstract

Enormous research is going on to reduce the size of portable electronic appliances and the use of self-contained power source is required to make more powerful and lightweight electronic devices without traditional batteries. Moreover for remote applications of the electronic devices it is very challenging as well as uneconomical to replace traditional batteries from the electronic systems. Piezoelectric energy harvester (PEH) may be used to power the small electronic devices but the major limitation of a PEH is generation of sufficient amount of energy essential for the autonomous operation of the portable electronics over the wide range of environmental vibration frequencies. Energy harvesters based on piezoelectric effect have attracted great research interest as the energy conversion efficiencies of piezoelectric materials are higher than those of electrostatic or electromagnetic materials. But linear PEH scavenge limited amount of power just near the resonance frequencies that rendered the linear PEHs useless in practical environmental vibration conditions. To overcome such complications, a Bistable Piezoelectric Energy Harvester has been proposed. To harvest the energy over the wide frequency range of environmental vibrations nonlinearity is introduced in the stiffness by mean of two neodymium magnets. The harvester has been modeled using Finite Element Method and validated with experimental study. The experimental results suggests that the efficiency of the bistable PEH is almost twice than that of its linear counterpart. The power reported in case of bistable system is 100% higher than the cantilever-type energy harvester and also significant over the wide frequency range. The performance of various piezoelectric materials in bistable configuration is also studied. The numerical simulation demonstrates that lead-free piezoelectric material family K0.5Na0.5NbO3 LiSbO3 (KNN-LS) exhibits better performance than the conventional lead-based piezoelectric material lead zirconate titanate (PZT). ZnO based nanogenerator is also studied. The complexity in the problem arises due to the existence of semiconducting properties along with the piezoelectric properties in ZnO nanowires. The developed model provides fairly accurate results when compared with the literature.