Environmental Engineering Reference
In-Depth Information
energy. Chapter 4 presents two types of piezoelectric-based VEH systems to
harvest impact or impulse forces from a human pressing a button or switch
action. The issues with the conventional approach of using electrical cables
in residential and industrial buildings to connect the appliance to the control
switch on the wall have been a cause of nuisance. To resolve the problem,
a batteryless and wireless remote controller has been developed to switch
electrical appliances such as lights and fans on/off in a wireless manner.
The experimental results verify that by depressing (1) the piezoelectric push-
button igniter or (2) the prestressed piezoelectric diaphragm material, elec-
trical energy is generated and stored in the capacitor. Once sufficient energy
is harvested, the batteryless and wireless remote controller is powered up for
operation.
An EH system itself has an inherent problem: the intermittent nature of
the ambient energy source. Hence, the operational reliability of the wireless
sensor node may be compromised. To augment the reliability of the wireless
sensor node's operation, Chapter 5 discusses two HEH approaches. A hybrid
WEH and SEH scheme is proposed to harvest simultaneously from both en-
ergy sources in order to extend the lifetime of the wireless sensor node. When
the two energy sources with different characteristics are combined, it is bound
to have the issue of impedance mismatch between the two different sources
and the load. To overcome the problem, each energy source has its own power
management unit to maintain at its respective MPPs. Experimental results ob-
tained show that the electrical power harvested by the optimized HEH system
is much higher than the single-source-based WEH. Chapter 5 also presents
a hybrid of indoor ambient light and TEH scheme that uses only one power
management circuit to condition the combined output power harvested from
both energy sources. An efficient microcontroller-based ultralow-power man-
agement circuit with fixed voltage reference-based MPPT is implemented
with a closed-loop voltage feedback control to ensure near maximum power
transfer from the two energy sources to its connected electronic load over
a wide range of operating conditions. Experimental results are provided to
validate the proposed HEH scheme by directly connecting the two energy
sources in a parallel configuration.
Other than EH, Chapter 6 also demonstrates an alternative means to re-
motely power low-power electronic devices through WPT mechanisms. The
WPT mechanism uses the concept of inductive coupling (i.e., by harvesting
the stray magnetic energy in power lines to transfer electrical power without
any electrical connection). Experimental results obtained validate the per-
formance of the developed WPT system. To extend the WPT distance, self-
resonating coils, operating in a strongly coupled mode, are demonstrated.
Detailed theoretical analysis of the WPT system are provided and then veri-
fied by the simulation results. Experimental validation of the performance of
the WPT system is provided.
Chapter 7 concludes the topic. It briefly states the focus areas and then
discusses the proposed solutions. It also lists the possible future work in this
line of research.
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