Performance improvement of magnetostrictive-type vibrational power generator using an optimization technique

Abstract

Expanding degrees of freedom in vibration systems is an effective way to improve the power generation efficiency of energy-harvesting devices from the vibrating source, since the system becomes responsive for a wide frequency range due to the appearance of multiple resonant peaks. A magnetostrictive-type vibration energy harvester that uses an iron-gallium alloy (Galfenol) has received much attention in recent years. A bending force applied at the tip of the cantilever yields a flux change due to tensile or compression stress, and the flux variation leads to the generation of voltage on the wound coils. This energy harvesting technology has advantages over conventional types, with respect to size and efficiency, and it is extremely robust and has low electrical impedance. In this study, the differential evolution (DE), known as a kind of global optimization techniques, was introduced for the parameter design of the harvester that constituted a two-degree-of-freedom vibration system. Using DE, we numerically explored the best combination of spring constants and masses of the vibration system that maximized the electric power generation.