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Electromagnetic energy harvester and self-powered embedded system

Energy harvesting offers an important design option
for creating sensing and control elements without a requirement for
custom wiring or batteries. The independent and care-free nature of
energy harvesting enables monitoring devices to penetrate wider and
deeper into our daily lives, making accommodation of fine sensing
and control for condition-based maintenance ever more feasible.
Finer granularity in sensing and control, which is the future of
energy efficiency, alone is an immense benefit as it can reduce
time and cost associated with a potential repair. Combined with
condition-based maintenance, it can prevent potential down-time of
a machine under monitoring. An exciting possibility creates a
"self-powered" embedded system with an integrated energy harvester
for electromechanical diagnosis. This non-intrusive energy
harvester is designed to extract energy from magnetic fields around
a power line of a load, in the manner of a current transformer. In
contrast to the conventional usage of magnetic elements, such as
transformers and inductors, the analysis on this "current
transformer" reveals a critical result: for any given core for any
particular application, power harvest is maximized when the core is
permitted to saturate at an opportune time in the line cycle. The
design of this integrated energy harvester is fully explored in the
thesis, including: development of new models to incorporate a fully
saturating magnetic core for simulation; designs of power
electronics circuits for maximizing power harvest; and integration
of the harvester into the embedded system as a practical power
supply. The design of a self-powered and low-power embedded system,
vibration assessment monitoring point with integrated recovery of
energy (VAMPIRE), is discussed in depth in the thesis. The overall
architecture of the embedded system is first presented, followed by
designs of individual subsystems, the power package and the sensor
package. In the power package, initialization, energy buffer, power
interfaces, power regulation, and microcontroller design are
explored. In the sensor package, power budget, sensors, data
storages, storage management, wireless communication, and
corresponding user interfaces are explored. Finally, impedance
spectroscopy for an electromechanical load is discussed. Using the
electrical and vibrational data that are nonintrusively collected
from electromagnetically self-powered embedded system, structural
issues of the load, i.e., changes in the stiffness of mounts and
the imbalance of a shaft, can be clearly identified, making it
feasible for this self-powered embedded system to be used for
condition-based maintenance.