A rotation energy harvester employing cantilever beam and magnetostrictive/piezoelectric laminate transducer

This paper presents an energy harvester employing a cantilever beam and a magnetostrictive/piezoelectric (ME) laminate transducer to transform rotation energy into electrical energy. The harvester has a magnetic circuit attached to the free end of the beam, and the ME transducer is placed in the air gap of the magnetic circuit. When the harvester is attached to a host structure rotating around a horizon axis, the alternation of the gravity component causes the beam to vibrate along its transverse direction. The vibration induces an alternating magnetic field applied on the transducer, which causes the ME transducer to generate electrical power. Based on Hamilton principle and the assumed mode method, the dynamic equation is derived to study the influences of the nonlinear dynamic behavior of the harvester on the energy harvesting. A prototype is fabricated and tested. The experimental results are in agreement with the analytical results. The maximum voltage is achieved at the second-order super-harmonic resonance rather than the main resonance, when the rotation rate is 588 rpm, and a power of 157.4 μW is obtained across a 3.3 MΩ resistor.