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Bimorph Piezoelectric Energy Harvester at Low Frequency
Published in Institute of Electrical and Electronics Engineers Inc.
This paper reports on the design and analysis of a bimorph piezoelectric energy harvester using polyvinylidene fluoride films (PVDF) as sensing element. The cantilever based energy harvester consisting of piezoelectric bimorph is clamped to the vibrating source at one end and with proof mass on the other end. The electrodes for measurement are placed on either side of the PVDF films and a ground/reference electrode is embedded within the bimorph structure. To enable the vibrating end, the device is modeled with sinusoidal body load and the analysis is done in a vibrating reference frame. The device is designed and finite element model (FEM) simulation is done in COMSOL Multiphysics. The performance of the energy harvester is accessed by three types of analysis. First the frequency response of the device is performed that shows the resonant frequency occurs at 21 Hz at a peak output voltage of 0.65 V for a mechanical input power of 1.9 mW resulting in an electrical output power of 7.3 μW. Then the load response of the device is performed which shows that the maximum output is obtained at a load of 100 kΩ for an input frequency of 21.5 Hz and an acceleration of l g. Finally, the acceleration dependence is performed for a load of 30 kΩ and acceleration of 1 g that result in a peak output voltage of 3.2 V, electrical output power of 180 μW for a mechanical input power of 0.047 W at an acceleration of 5 g. This work significantly proves that the piezoelectric energy harvester using PVDF films are capable of generating maximum electric output power at low frequency when the excitation frequency matches the eigen frequency of the device. © 2020 IEEE.