Electromechanical Energy Scavenging from Current-Carrying Conductors

This paper describes a novel method for scavenging energy for electric power systems sensing applications by the use of permanent magnets that couple to the magnetic field generated by an alternating current flowing through a nearby conductor. The resulting mechanical energy is converted to electrical energy using piezoelectric transduction. This electromechanical AC energy scavenging method is an attractive alternative to coil-based AC energy scavengers in cases where the scavengers cannot encircle the conductor. In such cases, the electromechanical AC energy scavenger has the potential to produce significantly more power than comparable coil-based methods. The components of an electromechanical AC energy scavenger are described in detail, and experimental data from prototypes that are fabricated and tested in our laboratory are shown. The 20 cm(3) prototypes generated up to 2.7 mW of power each from 20 A of nearby current. Theoretical power densities of electromechanical AC energy scavengers are compared to the power densities of representative coil-based methods, showing that in some cases the electromechanical AC scavengers can generate an order-of-magnitude more power than coil-based AC scavengers. This paper demonstrates that electromechanical AC energy scavenging is a potential method for powering small size low cost stick-on wireless sensor networks.