Ambient vibrations piezoelectric harvester array with discrete multiple low frequencies

This work presents an approach to enhance kinetic energy harvesting from low multi-frequency discrete ambient vibrations. It is based on an array of three piezoelectric harvesters each with a certain resonant frequency that is triggered at a specific frequency in the vibration environment. The harvesters used in this work are of commercially available cantilever beam type. Their resonant frequencies are experimentally estimated. They are compared with the theoretical values from the model and good agreements are found. During operation, each harvester is modeled as a voltage source with a resistance and a capacitance load (i.e. RC circuit). The proposed approach discretely broadens the frequency band of power harvesting process and makes it more efficient and more suitable for practical implementations.