Résumé:
A large number of studies have been published in the last decade on the possibility of harvesting
vibratory energy using piezoelectricity as a conversion mechanism. Several aspects have been
studied ranging from different electromechanical models through harvester forms maximizing
performance to electrical circuits allowing an improvement of the harvesting energy. By
spreading through the distribution electrical networks, the problem of harmonic pollution is
becoming more and more worrying with the increasing use of electronic components and
nonlinear loads, which leads to harmful consequences and therefore a malfunction of several
devices sensitive to this kind of problems. Active power filtering is one of the most effective
solutions to this problem. The contribution that brings this thesis, in the energy harvester and
improvement field, consists to design a new optimal wind vibratory energy harvester using
piezoelectric elements. The work of this thesis revolves around five objectives:
1. Design and experimental validation of a power generator based on piezoelectric
transduction and wind flow.
2. Development of an analytical model to predict the performances and explain the chosen
geometry of the piezoelectric wind energy harvester.
3. Development of an energy extraction circuit to maximize the harvested power by the
piezoelectric elements and adapt the generated voltages to a high level.
4. Design of a hybrid supercapacitors batteries system to store the harvested energy by the
wind piezoelectric generator and provide the power difference when an active power
imbalance occurs in the harvester system.
5. Development of an active filter compensation model based on piezoelectric harvester not
only to mitigate the harmonic currents and voltages in the distribution electrical networks
but also to compensate the reactive power on the source side.
In order to meet these objectives, at the beginning, we started with a reminder of the potential
sources of harvested energy and the different conversion types including piezoelectric
conversion and we have established a state of the art of the energy harvesting from piezoelectric
elements. Then we presented theoretical notions of piezoelectricity followed by a detailed study
of the piezoelectric phenomenon in order to use it in a vibratory energy harvesting structure and
we have exposed a state of the art of piezoelectric generators with a macroscopic structure. Next,
we have described bimetallic piezoelectric type structure as an example of application. After
that, we presented the design, modeling, and the description of the proposed wind piezoelectric
harvester, and we have established a literature review of the different generators models based on
piezoelectric transduction and wind flow. In addition, the experimental validation of the
piezoelectric generator model constituting our original contribution for that a large space was
reserved for the presentation of the design process, fabrication and experimental assembly of the
device after having developed a special analytical model. Besides, we showed how the extraction
of the harvested energy can be conceived in order to maximize the power and adapt the
generated voltages to the different electrical uses and how the storage of energy can be reached
by a hybrid supercapacitors batteries system in a piezoelectric transduction mode. In the last
step, we presented globally the problem of harmonics and the active filters as an effective
solution. In addition, on the one hand, we applied a group of 8 identical PZT generators to the
parallel active filter for current harmonics compensation, and on the other hand, we associated a
group of 8 GEPZT to the series active filter to react against voltage harmonics and in the target
to demonstrate its flexibility with piezoelectric systems.
