A Coupled Finite Element-circuit Analysis on Flexible PVDF Energy Harvester

摘要

Piezoelectric energy harvester (PEH) has attracted intensive attention due to its simple configuration, high power density and no need for extra power supply, and in particular, poly (vinylidene fluoride) (PVDF)-based PEH additionally shows flexibility and exhibiting promises in applications such as the power supply for wearable devices. However, the actual PVDF-PEH produces much lower performance than theoretical estimations. This is because on one hand the existing theoretical calculations are based on over-simplified models, on the other hand, the optimum resistive load of PVDF-PEH is too high to match in practical applications. In this paper, a coupled finite-element-circuit analysis is conducted for PVDF-PEH to give accurate simulation for the device performance. Besides, multi-layer PVDF membranes are used in our model which notably decrease the optimum resistive load. Phase difference between output voltage and mechanical z-displacement is studied: the external load meets the optimum value when the phase difference is 135°, providing an alternative insight into the load matching problem. Finally we have simulated an optimized device with four 50μm thick PVDF layers, which shows an output power density of 2.69mW/cm3 under 47.6Hz, 0.5g sinusoidal vibration and 10.76mW/cm3 under 47.6Hz, 1.0g sinusoidal vibration.