Design and Optimization of Backfolded Piezoelectric Microenergy Generators

Abstract

A piezoelectric micro generator is a device that is intended to supply power to a wireless internet of things (IoT) application. The generator accumulates power when undergoing mechanical stress by vibration from the surroundings. The micro generator is able to sustain power to the application without any external source of power. The objective is to propose a design for two different models that is optimized with respect to bandwidth, tolerance and low frequency spectrum. The first model is a single back folded beam stucture, while the second is a double folded beam structure. The optimisation was carried out with respect to resonant frequency analysis and frequency response of the design. The simulations were carried out with the finite element software COMSOL multiphysics 5.6 and post processed in Matlab. The total length, width of each beam and the length of the outer proof mass were the major factors in improvement of the bandwidth, tolerance and frequency spectrum. The final design of the single fold generator resulted in a bandwidth of 1181 Hz operating between 1100 and 2500 Hz with a tolerance of 236%. The final design of the double fold generator resulted in a bandwidth of at least 2500 Hz operating between 900 and 2500 Hz with a tolerance of 27.6% and 50.1%. The bandwidth for both models were calculated with respect to a 0.1V threshold.