Spatial Optimization of Piezoelectric Energy Scavenger from Current-Carrying Wire

Abstract

Harvesting energy by coupling a magnetic proof mass with current flowing through a wire has recently been investigated as a method to power wireless sensor networks. However, the location of the cantilever and magnet in relation to the wire is critical to optimize performance. The configuration of the wire and the stiffness of the cantilever are also critical for device performance. This paper investigates optimizing the spatial location of the energy harvester and magnetic proof mass in relation to the wire for smart grid applications. Two different types of wires (solid and braided) copper wires were used with varying current up to 20A. This is conducted using a macro-scale piezoelectric cantilever with the goal to gain insight to apply to micro-electromechanical devices. Two different piezoelectric cantilevers with varying stiffness were tuned to operate at 60 Hz resonant frequency, using NdFeB magnet. The magnets act as a proof mass to lower the frequency while also coupling to the magnetic field from the current carrying wire, generating a sinusoidal force. Experimental and finite element modelling determined that the optimal location of the magnet for a solid wire was between 33° and 40° depending on the cantilever stiffness.