Modeling and experimental verification of a fractional damping quad-stable energy harvesting system for use in wireless sensor networks

Abstract

This paper presents the theoretical modeling and experimental verification of a quad-stable non-linear electromagnetic-induction energy harvesting (QEH) system. The suspended magnet of the QEH system consists of two aluminum caps that are circumferentially filled with copper beads for smooth axial movement. A QEH system model having fractional damping is established. Experimental investigations reveal non-linear phenomena of magnet movement such as chaos and bifurcations. The quad-stable mechanism is analyzed by virtue of Poincaré sections, bifurcation diagrams, and stroboscopic sampling in relation to the suspended magnet length and QEH system configurations. The results indicate that the length of the suspended magnet is a key parameter, and its change can give rise to the subcritical and super pitchfork bifurcations as well as the saddle-node bifurcations. Compared with the linear oscillator and mono-stable nonlinear system, the QEH system by magnetic levitation oscillations can stimulate more singular points (i.e. equilibrium points) of the magnetic force potential, and thus possesses the capability of energy harvesting across a wider frequency range as well as deliver more output current to the electric load through snap-through movements of suspended magnets. Therefore it is capable of directly driving sensor circuits for use in the wireless sensor network.