A 500 Hz-wide kinetic energy harvester: Outperforming macroscopic electrodynamic arrays with piezoelectric arrays

Research based as well as industrialized harvester developments indicate that electrodynamic energy harvesters (EHs) outperform piezoelectric EHs in macroscopic designs for narrow banded resonance-based transducers. This paper investigates how multiple vibration EHs can be combined to a macroscopic array configuration that covers 100-600 Hz by aiming not on high resonance peak powers but on close spectral overlapping in lower power regions of 0.5 mW. The 500 Hz-wide array is able to harvest vibrational energy from a multitude of machinery, independent of vibration frequency determining shaft speeds or flows. The novelty of this paper consists in the result that combining piezoelectric EHs to arrays outperforms electrodynamic arrays with respect to their volumetric power density for 500 Hz-wide operation. Further optimization is reached by introducing nonlinearities for the piezoelectric array. The presented design allows a flat integration of piezoelectric EH-arrays as power supply for energy autonomous sensor systems.