Abstract
Advances in design and development of light-weight and low power
wearable and mobile devices open up the possibility of lifetime
extension of these devices from ambient sources through energy
harvesting devices as opposed to periodically recharge the batteries.
The most commonly available ambient energy source for mobile devices is
Kinetic energy harvesters (KEH). The major drawback of the energy
harvesters is limited effectiveness of harvesting mechanism near a fixed
resonant frequency. It is difficult to harvest a reliable amount of
energy from every forms of device motions with different excitation
frequencies. To overcome this drawback, in this paper we propose an
adaptive electromagnetic energy harvester which utilises spring
characteristics to adapt its resonant frequency to match the ambient
excitation frequency. This paper presents a prototype design and
analysis of an adaptive electromagnetic energy harvester both in
simulation and real. The harvester has tested using a specially designed
experimental setup and compared with numerical simulations. The proposed
solution generates 3.5 times higher maximum power over the default power
output and 2.4 times higher maximum frequency compared to a fixed
resonant frequency electromagnetic energy harvester.