Transcript Micro-energy harvesting

Micro-energy harvesting
• Testing the feasibility of
indoor harvesting from
routine motion in the
environment.
• A comparison of three
energy harvesters gathering
from linear motion produced
by a sliding door.
• Looking at piezo elements,
stepper motor generator and
faraday induction.
What is energy harvesting?
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Energy harvesting (also known as Power harvesting or energy scavenging)
is the process by which energy is captured and stored. Frequently this
term is applied when speaking about small autonomous devices, like those
used in sensor networks. A variety of different sources exist for harvesting
energy, such as solar power, thermal energy, wind energy, salinity gradients
and kinetic energy.
Piezo electric elements
• It is the inherent property of piezo electric material to
produce an electrical potential, high voltage - low current,
when put under strain, either deflection or compression.
• Used both micro-fiber composite (mfc) and traditional
ceramic types.
Stepper motor generator
• Produce power at low rotation rates
• Produces twice as much power as a dc motor
• Common and easily available
Electro-Magnetic induction
(Faraday’s law)
• Passing a magnetic field through a conductive coil
produces an electrical potential.
• Utilized a commonly available “shake flash light”
and circuit.
Early trials
• We initially worked on testing the feasibility of piezo
energy harvesting to find a method of capturing the energy,
rectifying it, storing it and measuring it.
QuickTime™ and a
YUV420 codec decompressor
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QuickTime™ and a
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are needed to see this picture.
MFC piezo transducer
- A woven fiber composite piezo produces three times the current
compared to a standard piezo.
-needs to be adhered well to a
flexible substrate for optimal output
-produced a cater lever with a counter
weight for optimal deflection and
energy output
QuickTime™ and a
YUV420 codec decompressor
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Data Logging: processing
->graph->text->movie
Piezo
solution:
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Stepper
solution:
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Graphing with mySQL + php
- Each Harvester has an xbee radio checking the
charge of the capacitor from its analog i/o pin and
sends the byte value and address in an api packet to
a base station every 60 sec.
- The base station, running processing, pulls apart
the api packet and logs the data by address into a
mySQL database running on a server.
- A php script grabs the analog data, converts them
into volts and then into joules and graphs them
online.
Xbee transceiver communication
Setup:
base station
atid 1955
atmy 0
atdl 1
atir
0x32
Atit 0x1
Atd0 Atd2 0x3
Atio 0x03
Atic 0x18
Atia -
joules1/2/3
1955
1/2/3
0
0xEA65
0x1
0x2
0x4
0x00
FlashLite phone app
-Pulls the last value from the
mySQL database via a php scipt
-graphs the three values as volts
as related to the xbee ref
- if a cap reaches the xbee max:
1023==3.3,
app allows the user to press a
button that places a call to the
asterisk server.
-acts as a testing management
tool
Flashlite -> Asterisk -> Processing
1. FlashLite places a call to the asterisk server asking them
to enter the extension.
2. User enters the dial plan where text to speech introduces
them and explains the interface.
3. A shell scipt then launches a Java file: JEAGIClient,
which grabs the call data.
4. JAEAGIServer.java runs on the server handing data back and
forth between asterisk and processing.
5. Processing parses the key values from the server that then
trigger an api at command to the local xbee.
Writing api AT commands to the xbee
//api packet to be sent out HIGH
port.write(0x7E);
//start byte
port.write(0x0); //MSB
int dataLength = 4; // set this to whatever your data length is currently
port.write(0x1 + dataLength); //LSB=data length + API id + frame id + two command bytes
int checksum = 0;
port.write(0x08); // send API command identifier
checksum = checksum + 0x08;
port.write(0x01); // send frame ID (set to 0 if no response is required)
checksum = checksum + 0x01;
port.write(0x49); // at command i
checksum = checksum + 0x49;
port.write(0x4F); // at command pin2
checksum = checksum + 0x4F;
port.write(0x08); //set pin high
checksum = checksum + 0x8;
println("Pre-checksum: " + checksum);
checksum = 0xFF - checksum;
println("checksum: " + checksum + " <-- this must be a single byte!");
port.write(checksum); //checksum
println("sending api packet to xbee!!!");
General Conclusion
1. Indoor energy harvesting is both feasible and necessary.
2. It is also very inexpensive and readily available.
3. All indoor environments have objects in routine motion, such
as doors opening and closing that can be converted to electrical
potential.
Conclusion: piezo harvesting
1. Piezo harvesting was the least effective form that we tested.
2. The frequency of deflection necessary to produce a usable amount
was not possible from installation on a door.
3. Effective Piezo transducers and costly: $160+ per
4. They produce very high voltage spikes and very low current,
thus, a perf- board was required rather than a bread broad due the
instantaneous rate of change.
5. Reasonable deflection was not possible from vibration so flicking
became the preferred means results in noise.
Conclusion: stepper motor generator
1. The greatest amount of energy was attained via the motor as
linear motion was transferred to circular.
2. Quickly 5volts was able to be stored in a . 33F cap.
3. Leakage of the cap was a problem as energy stored and released
are both exponential.
4. Cheap and readily available, small package and no extra noise.
Conclusion: electro-magnetic
1. Great potential to produce electricity, but a door was not the
right environment due its requirements for linear motion
and high frequency.
2. Very cheap and easily produced.
Link to resource wiki