Current Research and Development ofWireless Power Transfer via Radio Waves

and the Application [DML]

Apr. 7, 2017

Naoki Shinohara, Professor,

Research Institute for Sustainable Humanosphere, Kyoto University

shino@rish.kyoto-u.ac.jp1

Copyright© The use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author.

2

AbstractTheory, technologies, applications, and current R&D status of the wireless power transfer (WPT) will be presented. The talk will cover both the far-field WPT via radio waves, especially beam-type and ubiquitous-type WPT, and energy harvesting from broadcasting waves. The research of the WPT was started from the far-field WPT via radio waves, in particular the microwaves in 1960s. In recent years this became a hot topic again due to the rapid growth of wireless devices. Theory and technologies of antenna and circuits will be presented in case of beam-type and ubiquitous-type WPT. The industrial applications and current R&D status of the WPT via radio waves will be also presented.

Index Terms: Wireless Power Transfer, Microwave Power Transmission, Energy Harvesting, Rectenna, Phased Array,

3

BiographyNaoki Shinohara received the B.E. degree in electronic engineering, the M.E. and Ph.D (Eng.) degrees in electrical engineering from KyotoUniversity, Japan, in 1991, 1993 and 1996, respectively. He was aresearch associate in the Radio Atmospheric Science Center, KyotoUniversity from 1996. From 2010, he has been a professor in ResearchInstitute for Sustainable Humanosphere, Kyoto University. He has beenengaged in research on Solar Power Station/Satellite and MicrowavePower Transmission system. He is IEEE Distinguish Microwave Lecturer,IEEE MTT-S Technical Committee 26 (Wireless Power Transfer andConversion) vice chair, IEEE MTT-S Kansai Chapter TPC member, IEEEWireless Power Transfer Conference advisory committee member,international journal of Wireless Power Transfer (Cambridge Press)executive editor, Radio Science for URSI Japanese committee Cmember, , past technical committee chair on IEICE Wireless PowerTransfer, Japan Society of Electromagnetic Wave Energy Applicationsvice chair, Wireless Power Transfer Consortium for PracticalApplications (WiPoT) chair, and Wireless Power ManagementConsortium (WPMc) chair. 4

Kyoto and Kyoto University

5

KyotoWinter

Autumn

Spring APMC2018 will be held at Kyoto.

- Kyoto Univ. Data (2015) -

Professors : 1,032 (5,445 Employees)

Students : 13,569 (Under Graduate)

4,773 (Master), 3,671 (Ph.D)

Novel Prizes (Prof. Yamanaka, Prof. Yukawa,

Prof. Tomonaga, Prof. Tonegawa, Prof. Fukui..)

Main Campus

Uji Campus

Kyoto Univ.

Kyoto Univ.

Tokyo

RISH, Kyoto Univ.

Microwave Power Transmission Field Experiment in Kyoto Univ.

1993

Second MPT

Rocket

Experiment

- ISY-METS -

1994-95

Ground-to-Ground

MPT Experiment

1996

Retrodirective

MPT System

Open Experiment

1983

First MPT Rocket Experiment

In the World - MINIX-1992

MPT Experiment to

Fuel-free Airplane

- MILAX -

2001

Solar Power

Radio Integrated

Transmitter

- SPRITZ -

2009

Airship-to-Ground

MPT Experiment

6

Contents1. Overview of Wireless Power Transfer via Radio Waves2. Current R&D of WPT via Radio Waves3. Theory and technology of WPT via Radio Waves4. Introduction of Activities of WPT in IEEE5. Conclusion

7SHARP Airplane exp.

1987@CanadaMPT to helicopter

By W. Brown 1964, 1968MPT rocket exp.

1983 by Kyoto Univ., ISAS

Island-Island MPT (150km)in Hawaii2008 by Kobe Univ., NASA

8

Overview of Wireless Power Transfer

via Radio Waves

9

Utilization of Radio Waves

• Information, Broadcast :Information added (modulated) on carrier

(radio waves) (Information from transmitter)• Radar (Remote Sensing) :

Information (amplitude, phase, etc.) reflectedfrom target on carrier (Information from target)

• Heating :Energy conversion from radio waves to heat

• Power Transfer :Energy conversion from radio waves to electricity(Frequency conversion only form GHz(MHz) to AC/DC)

All Radio Waves, Light, and Electricity are

based on Maxwell’s Equations.

Various Wireless Power Transfer

Ｉ

Ｉ

H

Supply

User

Ｉ

Ｉ

H

Supply

User

L

L

C

C

Resonance of L and C

Transmitter

Transmitted

Power

Receiver

→PowerOnly Carrier for WPT

Very Narrow

Electric Power

To User

Frequency

Time and

Space

Inductive

Coupling

(Magnetic)

Resonance

Coupling

Capacitive

Coupling

10

E

V

V

Radio Waves

(Microwaves)

WPT Theory

Faraday’s law :

NS

Load

High

Frequency

Ampere’s law : H

IδH

NS

Coil

Electromagnetic Wave

(Radio Wave)Electric Field Electric Field

Magnetic FieldMagnetic Field

High

Frequency

Transmitting

AntennaReceiving

Antenna

Raidowave Power (Electric Power)Maxwell’s Equations

Inductive Coupling WPT

WPT via Radio Waves

H

0

Bdiv

Ddiv

t

BErot

t

DJHrot

11

)/( 2mW

HES

Radio wave itself is energy.

What we need is frequency conversion only.

Electromagnet

Brief History of WPT• 1864 Prediction of Radio Waves by establishment of

Maxwell’s Equation based on Ampere’s law andFaraday’s law. (Radio waves was found in 1888 byHertz’s experiment)

• Around 1900 Tesla carried out WPT experiment ofboth inductive WPT and WPT via radio wave (150kHz),-> faired

• 1960s W. Brown carried out beam-type WPT viamicrowave (2.45GHz) -> succeeded

• 1980s Commercial Products of inductive WPT (Shaver,IC card..)

• 1990s 1) RF-ID, 2) RF WPT toward Solar Power Satellitein Japan

• 2006 MIT group proposed resonance coupling WPT(revised inductive coupling)

• 2010s Various WPT – Standardization of inductiveWPT, wireless charger for EV, energy harvesting frombroadcasting waves, ubiquitous RF-WPT…

12

13

Current R&D of WPT via Radio Waves

Various Wireless Power Transfer via Radio Waves(a) Beam-type

(High efficiency with higher frequency)

(b)Ubiquitous-type (Low efficiency, like RF-ID)

(c) Energy Harvesting

(No power source)

Transmitter

Receiver

→Power

Time and Space

Information

Frequency

Wide

Electric Power

to User Receiver

→Power

Transmitted

Power

Transmitted

Power

Transmitted

Power

Transmitter

Transmitted

Power (Broad)

→ Electric

PowerOnly Carrier for WPT

Very Narrow

Frequency

Time and

Space

→ Electric

Power→ Electric

Power

14

(d) In Closed Area (like Waveguide)

Transmitter

Transmitted Power

Receiver→

Power

Power Density of TV/Mobile Phone in Nara, Japan

15Kitazawa, S., et al., “Field Test Results of RF Energy Harvesting from

Cellular Base Station”, Proc. of GSMM2013

Kanazawa Inst. Tech., “The 500MHz band low power rectennafor DTV in the Tokyo area”, Proc. of WPTc2016

16

Frequency plan at Tokyo area

Center

frequencyERP

TV

Stations

491MHz 11.5 kW MX

521MHz 69 kW CX

527MHz 69 kW TBS

533MHz 69 kW TX

539MHz 69 kW EX

545MHz 69 kW NTV

551MHz 68 kW NHK(Edu.)

557MHz 68 kW NHK

10km

15km

20km

Tokyo

metropolitan

area

TOKYO

SKYTREE

Measurement

points

25 km

Distance (km)2 4 6 8 10 20

0

0.5

1

-40

-30

-20

-10

-50

Outp

ut

dc v

oltage (

V)

Inp

ut

pow

er

(dB

m)

Input power

Output voltage

L type LPF

Cockcroft-Walton

type rectifier(m=2)

Diode

HSMS-285C

Load resistance terminals

1.6kWAntenna

Wireless-Powered ZigBee in Same Frequency Band

17

ON ONON

OFF OFF

ZigBee

Rectenna

Mic

row

ave P

ow

er

Zig

Be

e C

om

mu

nic

atio

n

Mic

row

ave P

ow

er

Zig

Be

e C

om

mu

nic

atio

n

Mic

row

ave P

ow

er

Zig

Be

e C

om

mu

nic

atio

n

Time

• We propose MPT-ZigBee system at

same frequency of MPT and ZigBee (at

2.45GHz) with scheduling algorism.

• We can increase a limit power without

any interference (5pW/cm2 (CW)

-> 1.91mW/cm2 (pulse, no scheduling)

- > 2.61mW/cm2 (pulse, scheduling)

Intermitted

(Pulse) MPTDevice Type

As join in network

As not join in network

End device 9.46 mW 61.8 mW

Ichihara, T, et al., “Study and Development of an Intermittent Microwave Power Transmission System for a ZigBee

Device”, Proc. of 2014 IEEE Wireless Power Transfer Conference (WPTc2014), 2014, pp.40-43

Weak point of ubiquitous network

society is a power source.

We propose a wireless power source with

microwave power transmission (MPT). In

most advanced system, we bring only a

receiving system, rectenna instead of heavy

battery. At first step, we try to charge a

battery via microwave power.

Receiving

System

Transmitting System

Ubiquitous Power Source (UPS)

Wireless Power source

in every time

and in everywhere“Ubiquitous Power Source”

Wireless

Charge

Shinohara, N., et al., “Study on Ubiquitous Power Source with Microwave Power Transmission”, Proc. of

International Union of Radio Science (URSI) General Assembly 2005, C07.5(01145).pdf, 2005 18

Demonstration of WPT-powered Sensors with Drone

19

自律プログラム飛行高度３０m～５０m

高度 約６ｍ～８ｍ

遭難者発見データ飛行経路情報マルチコプタ-動作情報ＷＢＬＳ動作情報

遭難者救援支援マルチコプタ基地

電波障害物

遭難者（救命カード保有）

中継器(必要に応じて）

電子基準点

遭難者救助対策本部

最大探査距離（ＴＢＤ）ｋm

マイクロ波電力

遭難者IDデータ

次期マルチコプター

by WiPoT, Kyoto Univ., Mini-Surveyor Consortium, Autonomous Control Systems Laboratory Ltd.

Demo (Jul. 16, 2015)

Applications : Rescue of victims, WPT-powered sensors at volcano,

Inspection of infrastructures (Bridges, Tunnels..)

Victim(with Rectenna-

Vital Sensor Card)Drone Station

for Rescue

Obstacle of Radio

ID Data of

Victim

Height 6-8m

Microwave powerVictim Data

Flight Path Data

Drone Health Data

WBLS Health Data

Transponder(If necessary)

Autonomous Programmed Flight

Height 30-50m

Next Term Drone

Electric Reference Point

Rescue HeadquarterFlying Drone

WPT-Powered

Sensor

4mMicrowave

(5.8GHz, -8.74W)

Maximum Search Distance (TBD) km

5.8GHz, 8.74W from 8x8 array (21dBi)

6.1mW Received at 2 rectennas (10.2dBi)

Commercial Products of WPT via Radio Waves

• Venture Companies of Wireless Charger of Smart Phone* ‘Cota’ by Ossia inc. (WiFi-Band) http://www.ossiainc.com/

* ‘Wattup’ by Energous corp. (2.45GHz and 5.8GHz Band)

http://www.energous.com/

• Japanese Company (Dengyo)of Battery-less Sensor

(900MHz-Band) http://www.den-gyo.com/solution/solution10_b.html

UHF Band Transmitter

(920 MHz Band)

Re

ctifyin

gC

ircuit

Tran

s-M

itter

Sensor &Micro Computer

A few m

Wireless Power

DataTransmission315 MHz Band

Wireless Sensor

20

KDDI (Big 3 Carrier

in Japan) supports

Ossia

Based on FCC-15

How Cota Works With Obstruction by Ossia

21

Unlike radio waves that pass through a human body, Ossia’s Cota technology considers our bodies to be obstructions and therefore power signals avoid them.

Obstructions Stay SafeIf an obstruction (humans, pets,

plants, etc.) is between the

receiver and the transmitter, the

reflections of the beacon signal

pulses (off of the walls/furniture)

will naturally find their way to the

transmitter.

Pulse PlaybackIn turn, the transmitter sends pulses that

mimic (playback) each incoming beacon

signal characteristics with opposite phase.

The outgoing pulses will have the exact

shape and take the same path of each

incoming beacon signal, using the same

reflections and creating a power signal that

is focused only on the receiver while

inherently avoiding obstructions.

Silicon Valley’s Rumor (2016)• iPhone8 will install chip of Wireless Charging via Radio

Wave by Energous

“With an Energous transmitter in your office, your phone will constantly be charging even while it’s in your pocket as you sit at your desk and work.”

22

https://www.bloomberg.com/news/articles/2016-01-29/apple-said-developing-wireless-charged-phone-for-

as-soon-as-2017-ijz3i4si

http://www.phonearena.com/news/Upcoming-iPhone-8-could-feature-wireless-charging-unlike-anything-

weve-seen-yet_id87639

23

MILAX Airplane Experiment(Japan, 1992)

With Kobe Univ., CRL, Nissan motor co., Fuji heavy industry co., ISAS in Japan

Transmitter(1.25kW)

Microwave(2.411GHz)

http://friendsofcrc.ca/SHARP/sharp.html

Electrical Beam Control with Phased Array Mechanical Beam Control

with Parabolic Antenna

Fuel-free Airplane MILAX

SHARP Experiment(Canada, 1987)

MPT to Flying Drone (Airplane)

24

Future Dream of MPT:

Solar Power Satellite (SPS)

1GW Solar Power Station

2kmf Solar Cells

2kmf Microwave Antenna

< 10,000 ton weight

36,000km

Wireless Power

Transmission

via Microwave

2kmf

Receiving Antenna

Energy Availability Factor

Ground PV

: < 15% (Night, Rain…)

Space PV (SPS)

: >90% (No Night in 36,000km Orbit,

No Rain by Microwave Propagation)

-> SPS is huge, stable, and CO2-less

Power Station

PowerSupply

-Control

PowerSupply-Main

AC

100V

AC

200V

(3φ

)

ReferenceSignal

RSCMaster Unit(R

EF O

UT)

DC

DC

BFN

HPA MDL

Sub-array

SUM

ERR

Radiator

TRK-RCV

DEM

CPUCARD

DIV

PowerSupplyCard

BFNC

BFN

D/C

Power Transmitting Module #1

RSCSlave Unit

Power Transmitting Panel

5.8GHz

SUM

Heat-Pipe

Feed

ANTFirst StageHPA MDL

BSC Section

BSC Section

Phase ControlSignal

RSC: Reference Signal Control BSC: Beam Steering Control BFN: Beam Forming Network BFNC: BFN for Control Signal

DIV: Divdier HPA MDL: High Power Amplifier

Module ANT: Antenna

: RF/IF Signal : Control Signal: Power Line : Thermal Path

BFN(Beam Forming Network)

HPA MDL (PAE >70%)

(High Power amplifier Module)

60cm x 60cm, ≧ 450W , ≦1.9kg

Sub-array Image

Power Transmitting Module Image

Transmitting ANT

(76 Sub-array ANT)

Sub-array ANT

______(4 elements)

Developed Thin Phased Array Antenna (FY2009-2014)by Japanese SPS Committee

(66mm x 66mm x 25mm(Thickness))

(120cm x

120cm) ,

5.8GHz,

1.8kWCW

Thin

Phased

Array

Developed by Mistubishi Electric Corp., Supported by METI 25

Power Density~350W/ /㎡at rectenna center

~10W/ /㎡at rectenna edge

WPT Ground Test

Microwave

Beam

MPT Experiment on Feb. 2015Thin-High Efficiency Phased Array with GaN MMIC

55m

2.5cm thickness phased array

GaN MMIC Amplifiers

5.8GHz, 1.8kW

Developed by Mistubishi Electric Corp. (Phased Array), IHI Aerospace (Rectenna Array), Supported by METI 2

27

Theory and technology of WPT via Radio Waves

28

Efficiency of Wireless Power Transfer via Radio Waves

RF Power

(Wired)

Frequency

Converter

RF Generator

DC Power

DC Power

(1) DC-RF conversionRF Power (Wireless)

(3) RF-DC conversion(2) Radio Wave Propagation

- Beam Efficiency -

Total Efficiency of WPT

= (1) X (2) X (3)

World Record : 54% (Beam-type, Lab.)by W. C. Brown in 1975

Magnetron

+ Horn Antenna

29

Rectenna – Rectifying Antenna –Radio Wave -> DC Power Converter

Brown&JPL Rectenna

(2.45GHz) 1970-75

Rectenna by Hokkaido Univ.

(2.45GHz) 1984

Rectenna byTexas A&M Univ.

(35GHz) 1992

Rectenna

byDENSO co.

(21GHz) 1997 Commercial Rectenna by DENGYO co. (2.45GHz) 2011

Rectenna

by Kyoto Univ.

(5.8GHz) 2001

Rectenna by Intel co.

(674 - 680 MHz) 2009

antenna

diode

antenna

diodeantenna

diode(backside)

antenna

diode

An-tenna

LPF

OutputFilterwith

Capa-citance

Radio Wave

DCTo Load

Frequency Characteristics of Efficiency of Rectenna

30

2.45GHz 5.8GHz 14GHz 24GHz 35GHz

100%

50%

0%

10GHz

60%

70%

80%

90%

40%

30%

20%

10%

100GHz45GHz 62GHz 72GHz

Frequency

RF-

DC

Co

nve

rsio

n E

ffic

ien

cy

: Diode : CMOS

antenna

diode

by Brown&JPL

(2.45GHz) 1970-75

by Texas A&M Univ.

(35GHz) 1992

Products by DENGYO co. (2.45GHz) 2011

by DENSO co.

(14GHz) 2000

MMIC by Kyoto Univ.

(24GHz) 2012

by École Polytechnique

Montréal (94GHz) 2015

antenna

diode

by Tel-Aviv University

(75-110GHz) 2014

532um x 910um

Input Poweror Connected Load

T.- W. Yoo and K. Chang, “Theoretical and Experimental Development of 10 and 35 GHz Rectennas”, IEEE Trans. MTT, Vol.40, No.6, 1992, pp.1259- 1266

Higher Order

Harmonics Effect

How do we increase the RF-DC conversion efficiency at energy harvesting?

31

RF-DC conversionefficiency

100%

V

I

VJ

(0.2-0.3V)

Vbr

(10-30V)

-VJ

Rdiode

“rectenna”region“detector”

region

VJ Effect

Vbr EffectDiode Maximum

Efficiency Curve

To increase the peak RF-DC conversion efficiency1) With low wRC diode2) High voltage at diode (almost breakdown)3) Higher harmonics combination (like class-F amplifier)

How to increase efficiency of rectenna

• Choose theoretically 100% circuit

• Reduce number of diode which is loss factor

– Recommend single shunt rectifier

• Choose diode with Low wRC diode

• Design circuit with higher harmonics combination(like class-F amplifier)

• Suppress higher harmonics re-radiation

• Match impedance at input and output

• To add high voltage (almost breakdown)

• (Additionally) consider combination of antenna32

Advanced Rectenna

• Wide Band

– Frequency

– Load

– Power -> especially low power

33Input Power

or Connected Load

Higher Order

Harmonics Effect

RF-DC conversionefficiency

100%

VJ Effect

Vbr EffectDiode Maximum

Efficiency Curve 800MHz

Example of Modulated Wave

(OFDM) for Harvesting

Expansion of optimum input, load, frequency, etc.

34Ferran Bolos, et al. (CTTC), “A UHF Rectifier with One Octave Bandwidth

Based On a Non-Uniform Transmission Line”. Proc. of IMS2016

• Broadband Impedance Matching (CTTC, Spain, 2016)

lg/4 line

Diode

Sector-type Class-F Load

Broadband F-class Load Rectenna by Kyoto Univ.

Normal Stubs

Sector Stubs

35

Advanced Rectenna

• Wide Band

– Frequency

– Load

– Power -> especially low power

36Input Power

or Connected Load

Higher Order

Harmonics Effect

RF-DC conversionefficiency

100%

VJ Effect

Vbr EffectDiode Maximum

Efficiency Curve 800MHz

Example of Modulated Wave

(OFDM) for Harvesting

Self-powered DCM Buck-boost Converter

37

Operating waveform

Expansion

Yong Huang, Naoki Shinohara, and Tomohiko Mitani, “A Constant Efficiency of Rectifying Circuit

in an Extremely Wide Load Range”, IEEE-Trans. MTT, Vol. 62, No.4, pp.986-993, 2014

Experiment on Self-powered RF-DC-DC Circuit

38

RF-DC rectifier + Buck-boost converter experimental

results : Comparison of efficiency-load

System efficiency with converter

Rectifier without

converter

Rectifier with converter

Buck-boost converter

Yong Huang, Naoki Shinohara, and Tomohiko Mitani, “A Constant Efficiency of Rectifying Circuit

in an Extremely Wide Load Range”, IEEE-Trans. MTT, Vol. 62, No.4, pp.986-993, 2014

Advanced Rectenna

• Wide Band

– Frequency

– Load

– Power -> especially low power

39Input Power

or Connected Load

Higher Order

Harmonics Effect

RF-DC conversionefficiency

100%

VJ Effect

Vbr EffectDiode Maximum

Efficiency Curve 800MHz

Example of Modulated Wave

(OFDM) for Harvesting

Expansion of optimum input, load, frequency, etc.

40“Transmission Line Resistance Compression Networks

for Microwave Rectifiers” Taylor W. Barton et al., MIT, USA

• Active Impedance Matching (MIT, 2015)

Selective Matching Circuit by Kagoshima Univ.

41

Consideration of Diode

42An E-pHEMT Self-biased and Self-synchronous Class E Rectifier

M. N. Ruiz and J. A. García, University of Cantabria, Spain, 2015

• Zero Bias Diode -> Low Efficiency (Bad diode parameter?)

• Self-biased and Self-synchronous Rectifier (Univ. of Cantabria)

Low Power Rectenna – How to add high voltage at diode

• Charge Pump -> High Voltage but Low Efficiency

• Output Filter Matching (Kyoto Univ. etc., Japan)

- 50% @ 1mW, 5.8GHz (2004)

• Standing Wave by Reflection

(Okayama Univ., Japan, 2004)

• Rectifying Circuit with Resonator

(Tohoku Univ. (2006), Toyama Univ. (2013), Japan)

- 40% @ 100mW, 900MHz

• High Impedance Circuit and Antenna(Kanazawa Inst. Tech. (2016), Japan)- 40% @ 100mW, 900MHz

43

RISH, Kyoto Univ. 41

Introduction of Activities of WPT

in IEEE

44

45

IEEE Wireless Power Transfer Conference (WPTc)

1st IMWS-IWPT (2011)2nd IMWS-IWPT (2012)at Kyoto, Japan

1st WPTC (2013)at Perugia, Italy

2nd WPTC (2014)at Jeju, Korea 3rd WPTC (2015)

at Boulder, USA

46

4th WPTC (2016)at Aveiro, Portugal

5th WPTC (2017)at Taipei, Taiwan

RISH, Kyoto Univ. 44

Conclusion

47

SPS

Buildings

Vehicles

Smart Energy

Communications –Power Coexistence

Energy Security

Infrastructure of Communications –Power Coexistence

Power Storage

Ubiquitous Power Source

Saving Energy

Our Dream : Wireless Power Society

Ubiquitous Power Source in Emergency

48

WPT Books

Wireless Power Transfer via Radiowaves (Wave Series)

Naoki ShinoharaISTE Publishing &

John Wiley & Sons, Inc., UK & USA2014.1

ISBN 978-1-84821-605-1(Paper Book and Kindle) 49

Wireless Power Transfer Algorithms, Technologies

and Applications in Ad Hoc Communication Networks

ed. Sotiris Nikoletseas, Yuanyuan Yang,

and Apostolos Georgiadis, Springer, 2016.7,

ISBN 978-3-319-46810-5

Online Journal of Wireless Power Transfer

Cambridge Press

http://journals.cambridge.org/action/displayJournal?jid=

wptCall for Paper!!