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Implementation of piezoelectric energy harvesting

Implementation of piezoelectric energy harvesting In footstep Tile at mutah university
by

Hanin Odeh

on 20 January 2015

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Transcript of Implementation of piezoelectric energy harvesting

Piezoelectric Conversion

Implementation of piezoelectric energy harvesting
In footstep Tile at Mutah university

Introduction of our project
Everyone is aware that fossil fuels are running out so researchers and scientists are looking at generating alternative energy sources, imagine that everyday practices such as walking and car traffic, for example,
can be used for the production and storage of clean and renewable energy, enough to run communications systems or street lighting!!


Energy harvesting

Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using
small-scale (≈1cm3) devices,

offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones,
and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries.

Overview of Energy Harvesting Technologies by Energy Source


1.Solar
2.Air flow

3.Radio Frequency Radiation


The power is collected by a suitably placed antenna and converted back into DC.
Since power transmission by radio frequency radiation requires
three steps:

1) Convert DC power into RF power,
2) Transmit the RF power to some point,
3) Receive the RF power and convert it back into DC power

4.Pressure Variations


There is very little research into using meso-scale devices to harvest energy from naturally occurring pressure changes. In
theory this is possible.
speculated that 7.8nW/cm3 could be gained from atmospheric pressure change through the day,..


Vibration energy perhaps represents the most abundant source next to Solar. Vibration can be found in a wide variety of natural, industrial, commercial and transport .
5.Vibrations and Human Movement


including
vehicle engine compartments, ships, helicopters and bicycles; floors speakers, walls, bridges, household appliances (fridges, washing machines), pumps and machinery, and humans (e.g. the human heartbeat).
,

History of Piezoelectricity


On August 2, 1880, brothers Jacques and Pierre Curie announced their discovery of the piezoelectric effect to the French Academy of Science: We have found a new method for developing polar electricity in these same crystals which consists of subjecting them to .variations in pressure

Piezoelectric Conversion
Certain materials, which can be either naturally occurring such as cane sugar, quartz, Rochelle salt and bone, or man-made such as barium , are piezoelectric;

that is: they will produce an electric charge when subjected pressure or conversely, they will physically deform in the presence of an electric field.


Piezoelectric Effects


The following constitutive relations are used to describe the direct and converse piezoelectric effects:


a.Electromagnetic conversion


According to Faraday's law of induction, when a wire is moved relative to a magnetic field, or vice .versa, an electromotive force is created

b.Electrostatic conversion


Electrostatic generators are comprised of two conductive plates that are electrically isolated via air, vacuum or a dielectric insulator (capacitor),

c. Piezoelectric conversion


Piezoelectric materials are non-central symmetric materials that can produce electrical charges on the surfaces when subjected to mechanical loads because of the change of the dipole moment within the materials

Piezoelectricity

Piezoelectric Effects


The following constitutive relations are used to describe the direct and converse piezoelectric effects:


where:

where
T
is the stress,
D
is the electric displacement,
S
is the strain
E
is the electric field,
εT
is the permittivity measured at constant stress
sE
is the compliance measured at constant electric field.


Working of piezoelectric materials
Mechanical compression or tension on a ceramic element changes the dipole moment, creating a voltage

Compression along the direction of polarization, or tension perpendicular to the direction of polarization, generates voltage of the same polarity , or compression perpendicular to direction of polarization, generates a voltage with polarity .

These actions are generator actions, where by the ceramic element converts the mechanical energy of compression or tension into electrical energy.

There are Different piezoelectric benders, such as cantilever, diaphragm, cymbal and drum.....
A cantilevered PEH can consist of one, tow or multiple piezoelectric layers which will be discussed as follows.
1.Cantilever
A multimorph cantilever has more than ..two PL's
The PL's were in parallel connection. They showed that the voltage output was inversely proportional to the number of PL's

A piezoelectric bimorph cantilever consists of two PL's sandwiching a NPL as shown in Figure .
Typically the two PL's consist of the same materials of the same
dimensions thus the strain neutral plane is in the middle of the cantilever thickness

A piezoelectric unimorph cantilever (PUC) consists of a piezoelectric layer (PL) and a non piezoelectric layer (NPL) as shown in Figure








Above and below the strain neutral plane, the strain/stress is of opposite signs but the same magnitude. Thus the net strain/stress in the PL is zero and no net charges can be generated.

Energy Harvesting
2.Buzzers Piezoelectric

The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying principle
This image shows the circular shaped diaphragm connected to the rest of the electronic components.

(diaphragm)
Foot step-Energy tile
the objective of our prototype is to show the Piezoelectricity phenomena ,Since The kinetic energy of walking people converts into electricity by using bras piezoelectric" buzzer"


Human Flow statistics at Mutah University's Main gate-left entrance



Mutah University has 2 gates for each gate there are 2 entrances
We have calculated the average human flow at main gate-left entrance By two methods
1- Estimation of human flow
2- Statistical Survey
Estimation of human flow

At First, We obtained Our data From the Admission and registration unit,
As written below:


-Total number of students: 22119

-Total Number of employee: 2100

-Total Number of students’ Permission of driving a car inside the campus: 50

-Total Number of employees’ Permission of driving a car inside the campus:2000
-Expected number of visitors/day: 200


At General, lectures schedule of Mutah University is divided into two times:
1
.Sunday/Tuesday/Thursday
2
.Monday/Wednesday:
We assumed equal students number for each time which is….

(22119-50)/2=11035
student per day
At most ,Mutah University’s employees are full time
11035+2100+200-2000=11335
person /day
“Assumption is one person in each car”


For one entrance
= 11335/4=2834
“Since there are 2 entrance for each gate” Expected Human Flow rate per hour
=2834/6=472
person/hour /entrance


Statistical Survey


The previous flow rate represents the minimum value ,hence there are lot of students cross the Entrance more than one time each day

So we had decided to make a statistical survey at the left entrance of Mutah Main Gate, for different period of time ,and for different days by counting each person that crossed the gate, then we have Calculated the Average flow, as shown in the table and figure-


Circuit Design


Input (Compression of Mechanical Tile)

Our design would have us construct a floor tile using Brass Piezoelectric (Buzzer).

Our input will be a floor tile that lowers a few millimeters, displacing the electrons in the Brass, generating our voltage.



Mechanical to Electrical Conversion (Compression of Brass Piezoelectric)

This is simply when a person’s kinetic energy displaced on the tile compresses the Brass Piezoelectric, generating a transition from mechanical energy to electrical energy. This is the technology block of our system.

AC/DC Converter (Bridge Rectifier)

We need a DC source because if we decide to power an energy storage device we will need to provide that with a DC source. Our AC/DC converter is built from a bridge rectifier type schematic

Temporary Storage (Capacitor Bank)


The signal since we are expecting it to be small. We also have a storage delay setup so that we can output our energy in a large amount instead of a steady low amount. We do this by storing energy in a group of capacitors.

will have each capacitor slowly charging

We use the Zenner diode for protects the capacitor from increasing voltage
Output (LED Load)


The output will be an LED load. The output receives electrical energy from the temporary storage once the capacitors are charged. This is where we physically witness the energy generation from kinetic energy and is where we show the ability to harness and transform otherwise wasted kinetic energy into electrical energy.


Piezoelectric Buzzer Circuit


Testing and verification

Based on our previous calculations of human flow for each second there is 0.4 step which means 2.5 s/step , we’ve done 3 tests to maintain the characteristics of the circuit , under
mechanical load 60 kg …
As written below:


Case 1:

Mechanical stress applied on One Piezoelectric Buzzer , one capacitor 100uF . See figure


this figure shows the relationship between open-circuit output voltage& time

The current varies from 0.3 to 17 microampere
The average current =8.65 microampere
Average step voltage= 0.05 volt
Average power for each step = 0.4325 micro watt


Case 2 :

6 connected buzzers
i= 39-25 micro A
power generated for each step = 1.92*10^-6 W
for 2.5 s
shows the relationship between open-circuit ...output voltage & time

Box tile
The structural integrity of the box should not be a problem since as long as it is constructed properly it should be able to withstand 100 kg weight with no problem. The internal components should last a long time and may never need to be replaced.


Pro.Saloum Aljibury
supervisor
Since we deal with A high sensitive piezoelectric elements ,the Box design represents a big challenge for us under current conditions ..

Construction of Brass
Piezoelectric element "Buzzer

We have used Brass piezoelectric element which the radius of material is 1.75 cm ,and the radius of Brass piezoelectric is 1.25 cm
..our elements didn't have support diaphragm

# shows the 3 connected ..buzzers

shows the relationship between open-circuit
...output voltage & time

polarity
Case 3 :
ANY QUESTION ...???

HANIN
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