Authors:
Elisabetta Boco
1
;
Valeria Nico
1
;
Declan O'Donoghue
1
;
Ronan Frizzell
2
;
Gerard Kelly
2
and
Jeff Punch
1
Affiliations:
1
University of Limerick, Ireland
;
2
Bell Labs and Alcatel-Lucent, Ireland
Keyword(s):
Energy Harvesting, Nonlinearity, Multiple Degree of Freedom, Electromagnetic Optimization, Modelling.
Related
Ontology
Subjects/Areas/Topics:
Energy and Economy
;
Energy-Aware Systems and Technologies
Abstract:
A 2DOF velocity amplified electromagnetic vibrational energy harvester is analyzed. The system consists of
two masses, one larger than the other, oscillating relative to each other in response to external excitation. The
large mass is designed with a centrally located cavity into which a second smaller mass is placed. This configuration
allows the larger mass to impart momentum to the smaller mass during impact, which significantly
amplifies the velocity of the smaller mass. By coupling high strength magnets (placed on the larger mass) and
a coil (embedded in the smaller mass), an electric current is induced in the coil through the relative motion of
the two masses. To intensify the magnetic field, the magnets are arranged with alternating polarity within the
soft-iron body of the larger mass. Between the two masses, and between the larger mass and the support, four
springs are placed. The smaller mass is designed to disconnect from the larger mass, when input vibrations of
sufficien
t magnitude are present, and this leads to significant nonlinearity in the system response, which is well
described by its transfer function. The nonlinearity leads to an increased bandwidth over which the system
can harvest energy. As a further improvement, the energy harvester is optimized by changing the properties
of the coil. Four different coils are compared in terms of their voltage and power output. Finally, a theoretical
model is proposed in order to predict the optimal configuration.
(More)