Regular Article

Energy harvesting from stray power-frequency magnetic field employing a piezoelectric unimorph based heterostructure

¹ School of Information Engineering, Baise University, 533000 Baise, P.R. China
² College of Electric and Information Engineering, Zhengzhou University of Light Industry, 450002 Zhengzhou, P.R. China
³ Department of Mechanical and Automation Engineering, Xiamen City University, 361008 Xiamen, P.R. China

^a e-mail: weiheky@yeah.net
^b e-mail: yr.lu@hotmail.com

Received: 4 December 2015
Revised: 15 February 2016
Accepted: 18 February 2016
Published online: 28 March 2016

Abstract

An energy harvester using a piezoelectric unimorph based heterostructure is presented to convert stray power-frequency (50 Hz or 60 Hz) magnetic field energy into electrical energy. The harvester consists a piezoelectric unimorph and a U-shaped mass structure. The U-shaped mass structure with two parallel bar magnets leads to a large rotary inertia for the given proof mass. An enhanced exciting torque is induced on the unimorph and the response of the harvester to the external magnetic field is strengthened. Under the resonant frequency of 50 Hz, the harvester produces a power of 154.6 µW with a matching load resistance of 199 kΩ at a magnetic field of 0.5 Oe. Through an up-conversion management circuit, the energy harvester can successfully drive a wireless sensor node with high power consumption (90 mW at transmitting and 18 mW at receiving) at a duration of 205 ms.