Post on 23-May-2018
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WIRELESS POWER TRANSFERPROF. DR. IR. HUBREGT J. VISSER
CONTENTS
1. Introduction
2. The History of Radiative Wireless Power Transfer
3. Basics and Limitations
4. Future Perspectives
5. Summary and Conclusions
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1. INTRODUCTION
1. INTRODUCTION
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DEFINITIONS
Wireless Power Transfer (WPT):A special form of energy
harvesting using dedicated electromagnetic sources.
Energy Harvesting: The process by which energy is obtained by
a device from external sources in the environment and
converted into usable electric energy.
Radiative Wireless power Transfer: WPT using radio waves.
Energy Harvesting
WPT
inductive radiative
1. INTRODUCTIONENERGY HARVESTING SOURCES
1831 Faraday dynamo WWII Philips dyno torch Modern dyno torch
1880 Curie discovery
of piezoelectricity
Enocean
wireless switchRPG7 fuse
Movement
Pressure
1821 Seebeck experiment
1948 USSR oil
lamp powered
radio
Temperature
gradients
1977 Voyager 2
Radioisotope
Thermoelectric
Generator
Light
1839 Becquerel experiment 1954 Bell Labs PV Modern PV
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1. INTRODUCTION
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APPLICATIONS AND POWER DENSITIES
APPLICATIONSReplacement of or charging batteries in small, wireless, autonomous sensors.
POWER DENSITIES
Picture source: http://smarthomeenergy.co.uk/what-smart-home
2. THE HISTORY OF RADIATIVE WIRELESS POWER TRANSFER
2. THE HISTORY OF RADIATIVE WIRELESS POWER TRANSFER
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1931: HARRELL NOBLE DEMONSTRATES RADIATIVE WIRELESS POWER TRANSFER
100MHz half-wave dipoles
Distance: 5 to 12m
15kW transmit power
Westinghouse laboratories
Demonstrated 1933-1934 at the
Chicago World Fair
2. THE HISTORY OF RADIATIVE WIRELESS POWER TRANSFER
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1964: WILLIAM BROWN DEMONSTRATES A WIRELESSLY POWERED HELICOPTER
• 5kW, 2.45GHz magnetron
• 3m diameter parabolic reflector
antenne
• 9m height
• 1.5m2 receive antenna
• 4480 diodes
• 270W DC power
• Raytheon Airborne Microwave
Platform (RAMP) project
2. THE HISTORY OF RADIATIVE WIRELESS POWER TRANSFER
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2017: HOLST CENTRE / IMEC & TU/E
2007
2009
2011
2013
2013
2014
2015
2016
2017
3. BASICS AND LIMITATIONS
3. BASICS AND LIMITATIONS
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DECREASE OF POWER
PT
Radio waves spread spherically.
For every distance-doubling, the power density [W/m2]
decreases with a factor 4.
Restrictions are not put on the transmit power
only, but also on the transmit antenna: EIRP
For GSM: 0.003 W/m2 (0.3 W/cm2)
For a 4W (EIRP) source at 5 m distance: 0.013 W/m2 (1.3 W/cm2)
3. BASICS AND LIMITATIONS
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EXPECTED RF POWER
PTPR
r
The receive antenna also determines the received power.
example: 4W EIRP at 5 m distance
Patch antenna, 6 cm x 6 cm, 2.4 GHz
RF power on antenna: 58 W
3. BASICS AND LIMITATIONS
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RECTENNA (RECTIFYING ANTENNA)
3. BASICS AND LIMITATIONS
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INCREASING THE DC VOLTAGE
Resonant grid with diodes
3. BASICS AND LIMITATIONS
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RESONANT DIODE GRID
3. BASICS AND LIMITATIONS
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POWER MANAGEMENT
• 30 W DC continuous at 10 m distance (3W EIRP source)
• 60 mW DC for 40 ms, every 2 minutes, at 10 m distance (3W EIRP source)
3. BASICS AND LIMITATIONS
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RECTENNA DEMO
4. FUTURE PERSPECTIVES
4. FUTURE PERSPECTIVES
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RECTENNA MINIATURIZATION AND INTEGRATION
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
• Use distributed radiators
• Combine radiation
patterns smartly
• Create pockets of high
energy density
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
Combining in frequency
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
Combining in time (pulsing)
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
Combining in time (pulsing)
&
Phase-shifting (beam-steering)
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
t = t0 + 10ns
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
t = t0 + 30ns
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
t = t0 + 50ns
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
t = t0 + 68ns
4. FUTURE PERSPECTIVES
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CHARGING PHONES ON A DISTANCE
t = t0 + 90ns
5. SUMMARY AND CONCLUSIONS
5. SAMENVATTING EN CONCLUSIES
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1. For practical radiative WPT creating enough voltahe and power are challenges;
2. WPT can be realised with a large collecting aperture;
3. For a small collecting aperture we need voltage boosting;
4. Through careful co-design of rectifier and antenna radiative WPT is feasible;
5. Charging cell phones remotely will become feasible by employing distributed, transient
transmitters;
6. For that research (and funding!) is necessary.
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