Power Generation Using Piezoelectric

DevicesMitsuki TsubooDaisuke HamazakiYuki FunazawaKyosuke Horiuchi

What Is a Piezoelectric Device?・ 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)

Research Instruments

How on Earth Did We Come Across PDs?

Power Problems 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.

We got interested in the problem and decided to find the solution.2012

2010

91

62

2

32

7

6CoalNuclearOther

%Thermal power generation

62% 91%

Alternative Energy

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

station can generate in a day, you have to press a PD

with your finger…

100,000,000,000,000,000,000 times.

Solar energy Biomass energy

Geothermal energy Wind

energyVibrational energy Solution

!!!

OutlineExperiment 1

Experiment 2

Experiment 3

Drop Test

DC / AC

The Best Circuit

Confirm a PD’s performance in our experiment by drop test

See if the PD allows DCor AC to flow

Create three types of circuits and examine which is thebest

Experiment 1~The Relationship Between Height and Voltage~

Drop Test

(50 [mm] = 2.0 [in] )

Drop Machine This machine dropped a small ball on a PD from a height of 50mm or 100mm and an oscilloscope measuredgenerated voltage.

Results and DiscussionHeight [mm] 50 100

Average voltage [V]

107 115Trial : 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 deformationability of the PD.

Now the PDs only have to be connected…?

What’s wrong?

Experiment 2~Can AC / DC flow through the PD?~

AC / DC 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

Ammeter

PD

Rectifier

… considered sounding showed current flowing

Results and DiscussionIn case of DC, The DC circuit didn’t sendcurrent. However, it sent current only when it was pushed.

But…

In case of AC, The AC circuit was allowed toflow into the PD without Pushing it.

But...

Simultaneously

■ 　 Associated wave

Experiment 3~The Best Way to Connect them?~

The Best Circuit

Precondition ・ Eventually convert AC into DC ・ Push them simultaneously ・ Connect PDs in parallel

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 more electric current than that in circuit 1.

Type 1D-1, R-1 Type 2

D-2, R-1

Type 3D-2, R-1

Type 4D-2, R-2

D (PD)R (rectifier)

ResultsType PD Rectifier Connection method Current level

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.

The best ways to connect are type 2 and type 4. But…

Connection ProblemsIn 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

Summary・ 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.

Practical UseDifferent Method

Moderate PressureMore Tries

40 50 60 70 80 90 100 1100

20

40

60

80

100

120

140

Height [mm]

Vol

tage

[V]

PD Dropped from 100 mm

Two PDs connected in series and pushed them simultaneously

Ten PDs connected in series and installed a diode

Next Plan・ More tries・ A large volume of data

Our expectation

What is the shape of the graph in experiment 1?

Is there another effective method?

We tried setting PDs on a slipper…

Push them simultaneously!

Require many rectifiers!

? Another different idea?

Thank You for Listening