Comparison between electromagnetic and piezoelectric seismic vibration energy harvesters

This paper contrasts the principal characteristics of seismic harvesters using either electromagnetic or piezoelectric transducers. The electromagnetic seismic harvester is formed by a cylindrical magnetic element with an inner gap where a coil is housed. The two components are connected via soft springs and the coil is fixed to the case of the harvester. The piezoelectric seismic harvester is formed by a cantilever beam with a small block mass at its tip. The beam is fixed to the harvester case and is equipped with piezoelectric patches, which are bonded on its top and bottom surfaces. The two systems are modelled with consistent electro-mechanical lumped parameter models. This allows the derivation of a unified formulation for the energy harvesting and thus a direct comparison of the electro-mechanical response and energy harvesting properties of the two harvesters. The study presented in this paper is limited to the case of energy harvesting from tonal ambient vibrations.