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Mitsuki
Daisuke
Yuki
Kyosuke
Tsuboo
Hamazaki
Funazawa
Horiuchi
・Piezoelectricity
(a phenomenon of electricity
caused by pressure or vibration)
・Piezoelectric device (PD)
(a machine that responds to stress or vibration)
・Dimensions
(35 x 35 x 0.53 mm)
・Structure
(positive ions are located in the center of lattice)
・Abilities
(when impacted, it generates an AC voltage,
in contrast , when subjected to an AC voltage,
it vibrates slightly)
How on Earth
Did We Come Across PDs?
On March 11th, 2011, a powerful
earthquake struck Tohoku, which
created secondary disasters.
Some of them were power
shortages and radioactive
contamination, or power problems.
Thermal power
generation
62%
91%
2010
2012
62 %
91
32
6
27
Coal
Nuclear
Other
We got interested in the problem and decided to find the solution.
A thermal power station can generate a huge amount of
electric energy in a day. It’s about…
1.3 x 1014 [J]
To produce as much electric energy as a thermal power
Biomass
Vibrational
Solar
station can generate inGeothermal
aWind
day, you have to press a PD
energy
energy
energy
with your finger…
100,000,000,000,000,000,000 times.
!!!
Solution
Experiment 1
Confirm a PD’s performance
in our experiment by drop test
Drop Test
Experiment 2
See if the PD allows DC
or AC to flow
DC / AC
Experiment 3
The Best Circuit
Create three types of circuits
and examine which is the
best
~The Relationship Between Height and Voltage~
This machine dropped a small
ball on a PD from a height of
50mm or 100mm and an
o sci l losc op e me as ur e d
generated voltage.
(50 [mm] = 2.0 [in] )
Drop Machine
Height [mm] 50 100
Average
107 115
voltage [V]
Trial : 40 [times]
Average time : 4.5 [ms]
The higher the ball fell from the ground, the
higher voltage it made. Although the height was
doubled from 50mm to 100mm, voltage did not
double. This was caused by the deformation
ability of the PD.
Now the PDs only have to be connected…?
What’s wrong?
~Can AC / DC flow through the PD?~
We connected a power source, a PD and an electric
music box in a series circuit. And we changed
power source to DC or AC.
DC voltage AC voltage
PD
Ammeter
Rectifier
… considered sounding showed current flowing
In case of DC,
The DC circuit didn’t send
current. However, it sent
current only when it was
pushed.
But…
Simultaneously
In case of AC,
The AC circuit was allowed to
flow into the PD without
Pushing it.
But...
■ Associated wave
~The Best Way to Connect them?~
Type 1
D-1, R-1
As a control, we built
circuit 1 and ones which
had one more PD. Then
we examined what kind of
circuit is better to generate
m or e electr ic c u r r e n t
than that in circuit 1.
Type 2
D-2, R-1
Type 3
D-2, R-1
Type 4
D-2, R-2
Precondition
・Eventually convert AC into DC
・Push them simultaneously
・Connect PDs in parallel
D (PD)
R (rectifier)
Type
PD
Rectifier
Connection method
1
1
1
Basis
2
2
1
PDs are connected
opposite to each other
3
2
1
PDs are connected in
the same direction
4
2
2
Rectifiers are connected
to PDs one by one.
Current level
The best ways to connect are type 2 and type
4.
But…
In case of type 2,
The more PDs are installed,
the more difficult it is to
push them simultaneously.
In case of type 4,
We require the same number
of rectifiers as PDs.
Simultaneously
・The higher pressure that is applied to PDs, the
higher voltage they generate.
・The generated voltage is not in direct
proportion to pressure.
・To convert stress to electric energy efficiently, we
need to develop an idea for how the PDs can be
pushed or have the same number of devices and
rectifiers in the circuit.
・More
tries
the shape
of the
IsWhat
thereis
another
effective
We tried setting PDs on a slipper…
graph
experiment
1?
・A
largeinvolume
of data
method?
140
Push them
simultaneously!
Our
Voltage [V]
120
100
80
60
expectation
Require
many
Dropped from
100 mm
rectifiers!
PD
40
20
0
0
?
Another different
50
100
150
idea?
Height [mm]
Two PDs connected in series
and pushed them simultaneously
Ten PDs connected in series
and installed a diode