An efficient electromagnetic power harvesting device for low-frequency applications

Mechanical energy in the form of low frequency vibrations (1-100 Hz) can be commonly available and this energy type can be advantageously converted to electrical one by exploiting energy harvesting techniques. At the same time, in many applications, the devices that convert low frequency mechanical energy to electrical one should have a small size. An electromechanical power generator is proposed for converting mechanical energy in the form of low-frequency vibrations, available in the measurement environment, into electrical energy. The intended applications for the proposed electromechanical power generator, described in this paper, are for examples mechanical systems with low frequency vibrations (1-100 Hz). The operating principle is based on the relative movement of a planar inductor with respect to permanent magnets. The generator implements a novel configuration of magnets that is proposed and analyzed with the aim to improve the conversion efficiency, increasing the spatial variation of magnetic flux. Furthermore, the generator uses polymeric material as resonators, which have low-frequency mechanical resonances due to the low Young's modulus of the materials by which they are made. The different materials, with which the suspensions for the planar inductor were made, have allowed to compare different behaviors of the resonators: linear and nonlinear. The experimental results have shown, for a linear resonator, a vibration frequency of about 100 Hz with generated powers of about 290 and a harvesting effectiveness of 0.5%, while, for the polymeric resonator made by Latex, the vibration frequency is around 40 Hz with a maximum power of 153 mu W and a harvesting effectiveness of 3.3%. The proposed configuration can be adopted for its low profile, modularity and low-frequency vibrations in many applications from industrial to medical. (C) 2011 Elsevier B.V. All rights reserved.