Energy - Bayern Innovativ

Transcrição

Micro Energy Harvesting
Power Supply for Distributed and Embedded Systems
Philipp Bingger and Peter Woias
Albert-Ludwig-University of Freiburg
Department of Microsystems Engineering (IMTEK)
Laboratory for Design of Microsystems
Freiburg, Germany
Philipp Bingger, Peter Woias, Effiziente Elekronik, 1.12.2009
Sheet 1
Wire or battery … or what ?
rope
distributed and „embedded“ sensor
systems in greenhouses © Crossbow
sensor
tire pressure sensors
medical implants
© Vitatron
battery service person
(vertigo-proof)
Sensors in redwood trees
© University of California
Sheet 2
Micro Energy Harvesting: The Vision
wireless data link
Energy-Autonomous Embedded Systems
„always on“
no battery recharging or exchange
no power cords
sensor input
easy to install …
… at numerous application sites
wireless
microcontroller
energy and transmitter
microsensor
system
management
energy management
heat,
light
movement,
other bugs,…
energy
conversion
generator
materials
and
energy
storage
energy storage
Sheet 3
Micro energy harvesting – IMTEK‘s PhD program
Fact sheet
Research topics
financed by DFG and industry
3 associated members
22+1 PhD scholarhips
energy transduction mechanisms
materials for energy harvesting
energy storage and management
system considerations
start:
October 2006
run-time: 4.5 years (1st phase)
Associated Members
Members
Sponsors
Sheet 4
Piezoelectric bending generators: Principle
q = d 31 ⋅ σ piezo,11
dq
d
(d 31 ⋅ σ 11 )
I =
=
dt
dt
Design challenges
homogeneous mechanical stress ¨ higher output power
tunable resonance frequency
¨ broader application range, more power
smart system integration
¨ cheaper, easier fabrication
Sheet 5
Optimized vibrational piezo generator (2007)
E. Just et al., Proc. GMM-Workshop
“Energieautarke Mikrosysteme”, 2006
F. Goldschmidtböing, P. Woias,
Journ. Micromech. Microeng. 18, 2008, 104013
spectral output power (no seismic mass)
influence of a seismic mass
Sheet 6
Frequency-tunable piezo generator (2008)
Principle
force
Actuation force in the „arms“ will
stiffen the resonating beam and
thus change its resonance frequency
¨ high tuning range (22%)
¨ loss of Q factor with
increasing force
C. Eichhorn et al., Proc. PowerMEMS 2008,
Sendai, Japan, 309-312.
Sheet 7
Fabrication: Piezo-Polymer-Composites (2003)
feed
vent
molding form
electrical contact
piezo
disk
piezoceramic disk
with metal electrodes
molding form
mounting block
liquid
thermosetting
polymer
20 mm
polymer layer
seismic mass
vibration
Advantages
structure definition and piezo integration
in one single step
piezo disk
cured polymer
low-cost perspective via inject molding
extremely high design flexibility
actuators and generators in one single technology
Sheet 8
Impact-type piezo generator (2005)
M. Wischke et al., Proc. Transducers 2007,
Lyon, France, 875-878.
6 mWp @ 36N pulse (100 ms)
Advantages
stress-homogenized hinge design
for a maximal output power
high output power
high output voltage
stacked devices for power
multiplication
Sheet 9
Electromagnetic generators: Principle and examples
rotor
generator
U = −N⋅
dΦ
dt
P = 800 µW
multi-resonant generator
Univ. Hongkong, 2002
electromechanic
quartz clockwork
battery
Properties
AC currents from motion or induced AC fields
bad to fair voltage range (mV…V)
moderate source impedance (<10 kΩ)
P = 5 µW
rotatory generator of the
Seiko KineticTM wrist watch
Sheet 10
Electromagnetic generator in PCB technology
lid
spacer
wire-wound
coil
22 mm
permanent
mechanical
multi-resonant generator
magnet
resonatorUniv. Hongkong, 2002
Properties
output power:
330 µW @ 102 Hz and 1G
no-load voltage: 210 mV
(improved via modified coil design)
E. Bouendeu, J. Korvink, IMTEK – Laboratory for Simulation
Sheet 11
Thermoelectric generators (TEG): Principle
Seebeck voltage
ΔU = α ⋅ Δ T
Specific output power
relevant material combinations α [µV/K]
Al / p-Poly-Si
195
Al / n-Poly-Si
110
p-Poly-Si / n-Poly-Si
190...320
p-Bi0,5Sb1,5Te3 / n-Bi0,87Sb0,13
200...420
p =
Pelectric
A⋅ ΔT 2
Sheet 12
Thermoelectric generators: Examples
polysilicon
polysilicon
oxide
FOX
cavity
cavity
silicon substrate
P = 1 µW/cm² @ ΔT = 5 K
micro-TEG in planar CMOS
© Infineon, 2003
P = 3 µW/cm² @ ΔT = 1..3 K
micro-TEG from (1994) for the „Seiko Thermic“
(sold in small numbers from 1998 on)
Micro Peltier cooler (photo) and microTEG (SEM)
© FhG-IPM, MicroPelt
Sheet 13
3D micro-TEG
membrane with planar
top heat conductor (gold)
thermocouples (Al-poly-Si)
7500 thermocouples
10 mm
thermal
insulator
(SU-8)
air chamber
for thermal
insulation
Output power and no-load voltage @ 10K
bottom heat conductor
(silicon)
measured:
1.612 µW
6V
optimization potential: 36.3 µW
T. Huesgen et al., Sensors & Actuators A 145-146, 2008, 523-429.
Sheet 14
Bio fuel cells: Principle and application
pacemaker
Properties
output power:
2.3 … 3.3 µW /cm²
open cell voltage: 0.5 … 0.3 V
power requirement of a pacemaker: 10 µW
1,2
3,0
1,0
2,5
0,8
2,0
0,6
1,5
0,4
1,0
0,2
0,5
0,0
0,0
0
Power density in µW cm-2
S. Kerzenmacher et al., Journ. Power Sources, 2008
A. Kloke et al., Proc. Biosensors 2008, Shanghai
Cell potential in V
direct-oxidizing
glucose fuel cell
5
10
Current density in µA cm-2
Sheet 15
Energy densities of various storage concepts
hydrogen in metal hydrides (MH)
10.000
H2 in MH (< 2%)
1.000
Li-Ion
NiMH
H2 in MH (4%)
Lead Acid
100
40
20
10
100
1.000
10.000
energy density in [W h/kg]
Refs: J. Brodd et al, J. Electrochem. Soc.,
151 (3), 2004, K1-K11 and HERA
Hydrogen Storage Solutions, Germany
r
ze
ct r
o ly
fu e
lc
I on
e ll
El e
1
H2
1
Li -
capacitors
MH
0
Ni-
Electrolyte Cap.
60
ld
Ca
p
Gold Cap
10
batteries
Adenosine
Triphosphate
80
Go
energy density in [Wh/l]
Methanol
Faraday efficiency [%]
100
H2 in MH
(nanopowder)
high storage density of H2 in MH
acceptable (and improving)
efficiency of H2 fuel cells
¨ Would a „hydrogen battery“
make sense ?
Sheet 16
Hydrogen-based energy storage
19 mm
6 mm
6 mm
voltage [V]
power density [mW/cm²]
chip-integrated
fuel cell with Pd
storage
current density [mA/cm²]
0.5 mm thick fuel cell:
photograph (right) and
its electrical characteristics
G. Erdler, M. Frank, M. Lehmann, H. Reinecke, C. Mueller, Sensors & Actuators A 132/1
(2006), 331-336.
Sheet 17
Energy management
Requirements
start-up control
optimal impedance match between
generator, battery and load
voltage level transformation
active generator control
active rectification
supply voltage:
<1V
power consumption: a few µW
Solutions, microchips ?..... not available
today ( 2005).
….eventually
coming along
(2009)
Solutions, chips ? ….not
available today
(2004).
2163 µm
control ASIC for a capacitive
micro converter, Medinger,
Ph. D. thesis, MIT, and
Analog Devices, 1999
Sheet 18
Commercial low voltage step-up converters
3
¡ charge pumps
start-up voltage [V]
2,5
inductor-based
2
1,5
1
1998: 1.0 V
0,5
0
1970
1980
1990
year
2000
2010
2005: 0.3 V
photovoltaic cell,
TE generator
Sheet 19
Demonstrator: Remote Temperature Monitoring
Application szenario:
35,4 °C
Energyautonomous
sensor system
RF
transmitter
35,4 °C
Microcontroller
Energy management
and storage
Remote temperature
RF
sensing
at „heavy“
receiver
machinery
…
Temperature ?
Temperature
sensor
Vibration
Piezogenerator
Sheet 20
System set-up
Requirements
well-defined turn-on and turn-off
low-voltage operation
low-power operation
Sheet 21
Stacked impact-type piezogenerator
Technical data
maximum output power:
120 µW
optimal output voltage:
2.15 V
tolerance band:
± 0.2 V
Sheet 22
Low-voltage regulator with sharp turn-on
Characteristics
safe-operation supply voltage: 0.4 V ☺
max. power consumption:
25 µW
optimization potential: 1…3 µW ☺
Sheet 23
Why not buy … ?
Problems with today‘s ICs
no „real low voltage“
undefined sub-threshold
behaviour
limited functionality (not
specific for energy harvesting)
Sheet 24
Micro-Embedded Systems and
Micro Energy Harvesting
What is it good for ?
Sheet 25
Automotive applications
light
motion
acceleration
sound and vibration
flow
heat
engine temperature sensors
© Continental
air flow sensors
knock sensors
pressure
sensor
tire rotation sensors
….
solar-powered air conditioning
energy recovery from hot exhaust gases
© Alps
Sheet 26
Tire pressure monitoring - Piezotag
Tire Pressure
Monitoring Systems
(TPMS)
mounted opposite the tread
power generator (piezoelectric)
power management (rectify and smooth)
electronics, sensors (p,T)
and RF transmitter
works at speeds above 15 km/h
test 40,000 km → OK
© Piezotag Ltd, England, 2009
Sheet 27
Home and building automation
light
heat/cold
sound and vibration
flow
autonomous switch © enOcean
heat meters at radiators
autonomous temperature sensors
autonomous lighting sensors
door and window surveillance
room occupancy detection via footstep detectors
ventilation control
…
Sheet 28
AISIS-Project (BMBF)
Project goals
energy-autonomous sensor-system for tunnels to determine the damage
in case of (explosion, fire,…)
energy-harvesting-methods
(piezoelectric, thermoelectric, wireless energy transmission )
development of high-tensile building materials
development of evaluation-models
psychological research
project leadership:
5 cm
Sheet 29
AISIS-Project (BMBF)
© IMTEK, Germany, 2009
thermoelectric-concept
generator inside tunnel-wall
small temperature gradients
(ΔT = 2 K)
optimized thermal coupling
vibration transducer-concept
generator on tunnel-wall
mechanical → electrical conversion
multi-resonant transducer
with optimized mechanical coupling
piezoelectric or electromagnetic
Sheet 30
„Daily Living“, medical, wellness, sports,…
force
movement
flow
chem. energy
heat
stress-controlled prostheses
autonomous sensors and
implants (Retina, Cochlear,…)
patient monitoring
(downfall, faint,…)
autonomous sports equipment,
…
© Microstrain
Sheet 31
„Parasitic“ biomechanical generators
© Bosch, ca. 1930
P=5W
© Bionic Power
Burnaby, Canada, 2008
P = 0,25 W
MIT Media Lab,
Boston, USA, 1998
P=3W
Sheet 32
Non-parasitic“ biomechanical generators
© Freeplay Energy,
crank-powered radio
UK, 2003
„Pullman“ MP3-Player
© Martijn Pater, TU Delft, NL, 2000
„REGEN“ MP3-Player
© Chris Aimone and Tomek Bartczak,
Toronto, Canada, 2003
Sheet 33
Conclusion and outlook
First micro energy harvesters available
Power management system MUST be adapted to
the particular generator
Need for low power ICs for power management
Well-defined turn-on and turn-off
Safe-operation
Low power consumption
Medinger, 1999
Sheet 34
Thank you very
much for your
attention !
Sheet 35

Energy - Bayern Innovativ

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