RADIATIVE WIRELESS
POWER TRANSFER
driven by nanoelectronics innovation
Peter Lemmens – General Manager imec (Taiwan)
CONFIDENTIAL
1. ENERGY HARVESTING
Movement
1831 Faraday dynamo
WWII Philips dyno torch
Modern dyno torch
Piezoelectricity
1880 Curie discovery of
piezoelectricity
RPG7 fuse
1821 Seebeck experiment
1948 USSR oil lamp powered radio
1839 Becquerel experiment
1954 Bell Labs PV
Enocean wireless switch
Temperature
1977 Voyager 2 Radioisotope
Thermoelectric Generator
Light
Modern PV
CONFIDENTIAL
1. ENERGY HARVESTING
Source
Ambient Light
Indoor
Outdoor
Vibration/Motion
Human
Industrial
Thermal
Human
Industrial
RF
GSM Base Station
Available Power Density
Typical Harvested Power Density
0.1 mW/cm2
100 mW/cm2
10 W/cm2
10 mW/cm2
0.5 m at 1 Hz
1 m/s2 at 50 Hz
1 m at 5 Hz
10 m/s2 at 1 kHz
4 W/cm2
20 mW/cm2
100 mW/cm2
30 W/cm2
1-10 mW/cm2
0.3 W/cm2
0.1 W/cm2
100 W/cm2
CONFIDENTIAL
2. WIRELESS POWER TRANSFER (WPT)
(Non-Radiative) Near-Field Power Transfer
1961
General Electric
Inductively charged toothbrush
2007
Kurs et al., Science
Wireless Power Transfer via
Strongly Coupled Magnetic
Resonances
(Radiative) Far-Field Power Transfer
1901
Nikola Tesla
Idea to wirelessly
transfer energy
1931
Westinghouse
Wirelessly powering a
lightbulb at 5m, 15kW
CONFIDENTIAL
3. (NON-RADIATIVE) NEAR-FIELD POWER TRANSFER
loss
Rs
Vs
RF source
Cs
Rr
Ls
Lr
RL
Cr
Rectification and
power
management
Transmit coil Ls
resonated with Cs
+ High power
+ High efficiency
+ Standard
-
Short distance
Standard
Receive coil Lr
resonated with Cr
&
Asus, Blackberry, Broadcom, Dell, Fairchild, Freescale, Hama, Hitachi, HTC,
Huawei, IKEA, Keysight, LG, Microsoft, Motorola, Nokia, NXP, Omron,
Panasonic, Philips, Powercast, Qualcomm, Ricoh, Samsung, Sony, TDK, TI,
Toshiba, Toyota, and others
Acer, Asus, AT&T, Broadcom, Canon, Deutsche Telekom, Dialog, Fairchild,
Fujitsu, HP, Hitachi, HTC, Intel, Keysight, Lenovo, LG, Microsoft, Motorola,
Nordic, NXP, Omron, Panasonic, P&G, Qualcomm, Renesas, Rohm,
Samsung, Starbucks, Sandisk, Sharp, Sony, ST, TDK, TI, Toshiba, Witricity, and
others
CONFIDENTIAL
4. (RADIATIVE) FAR-FIELD WIRELESS POWER TRANSFER (WPT)
Source unintentional: RF harvesting
< 0.003 W/m2 = 0.3 W/cm2 (GSM900)
Source intentional: Wireless Power Transfer (WPT)
< 0.03 W/m2 = 3 W/cm2 (4W EIRP)
WPT governed by Friis transmission equation
gain receive antenna
PR  PT GT
received power
transmitted power
gain transmit antenna
wavelength
GR 
GR 

EIRP
4 2 r 2
4 2 r 2
2
2
Internationally, so far,
WPT effort has been
concentrated on the
rectenna
distance
Effective Isotropic Radiated Power
Subject to (inter)national restrictions
CONFIDENTIAL
4. (RADIATIVE) FAR-FIELD WIRELESS POWER TRANSFER (WPT)
Monitoring temp, humidity and gas
distributions
Cold chain logistics: remote temp monitoring
Remote cell phone
powered food sensors
CONFIDENTIAL
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CONFIDENTIAL
5. STATE-OF-THE-ART IMEC
imec BEST-OF-CLASS
due to
modeling and optimizing
antenna-rectifier-load
combination
CONFIDENTIAL
PCB OVERVIEW RECTENNA
An increase in circuit efficiency of 18–25% compared to state-of-the-art
10
CONFIDENTIAL
5. STATE-OF-THE-ART IMEC
Transmitter: 3W EIRP, 868-915MHz
30µW continuous DC power
up to 5m distance
60mW DC power during 40ms every 2
minutes up to 12m distance
CONFIDENTIAL
5. STATE OF THE ART – POWERCAST & IMEC
www.powercastco.com
Tx: 3W EIRP @ 915 MHz
Powercast available
power vs distance for
shown rectenna
Imec rectenna with application
Powercast rectenna
Imec available power vs
distance for shown
rectenna
CONFIDENTIAL
6. IMEC WIRELESS POWER TRANSFER –ONGOING RESEARCH
Harvester tests
On-Metal Miniature
Rectenna
Tx Antenna
Hardware realized. Tests
with harvester
successfully performed.
Next generation 2.4 GHz.
Efficiency improvement
•
•
Wave shaping/ modulation
Diode modeling
Topics: multi-beam, NearFar field, analysis tools,
etc.
Patent for hybrid
inductive /radiative
system granted.
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CONFIDENTIAL
7. SUMMARY
• Far-field WPT, obeying ISM EIRP limits has become feasible.
• In practice this means tens of milliwats, during tens of milliseconds, every
one or two minutes, on distances beyond 10m.
• This is possible through a careful co-design of rectifier and antenna.
• We realize far-field RF harvesters that are :
•
•
•
•
Smaller
More power efficient
Produce higher DC output voltages
Operate at lower RF input power levels
Compared to any reported academic or commercial device
operating at the same frequency (UHF 900MHz).
CONFIDENTIAL
World-leading nanoelectronics
technology provider
CONFIDENTIAL
Industry-relevant solutions
CONFIDENTIAL
30+ YEARS
GLOBAL EXCELLENCE
IMEC Headquarters, Belgium
CONFIDENTIAL