Group 5 Wireless Oower

Wireless Power TransmissionWireless Power TransmissionEE563-Graduate SeminarFall 2004 Group 5

Alan Chun-yip YeungLeanne CheungJeff Samandari

Wehibe BelachewTesfa Mael

Jose A. Becerra

Presentation OutlinePresentation Outline

1. Introduction / Background1. Introduction / Background

2. Theory of Wireless Power Trans. 2. Theory of Wireless Power Trans.

3. Major Research Projects 3. Major Research Projects

4. Comparison of Efficiency … 4. Comparison of Efficiency …

5. Proposed Project/Experiment5. Proposed Project/Experiment

6. Conclusion6. Conclusion

1. Introduction / Background1. Introduction / Background

OutlineOutline• History/Background• Solar Power Satellite• Microwave Power Transmission• Conclusion

Reference:http://www.kentlaw.edu/classes/fbosselm/Spring2004/PowerPoints/Wireless%20Power%20Transmission%20-%20Soubel.ppt

Background, Nikola TeslaBackground, Nikola Tesla• 1856-1943• Innovations:

– Alternating current– Wireless power

transmission experiments at Wardenclyffe

WardenclyffeWardenclyffe• 1899

– Able to light lamps over 25 miles away without using wires

– High frequency current, of a Tesla coil, could light lamps filled with gas (like neon)

1940’s to Present1940’s to Present• World War II developed ability to convert

energy to microwaves using a magnetron, no method for converting microwaves back to electricity

• 1964 William C. Brown demonstrated a rectenna which could convert microwave power to electricity

Solar Power from SatellitesSolar Power from Satellites

• 1968’s idea for Solar Power Satellites proposed by Peter Glaser– Would use microwaves to transmit power to

Earth from Solar Powered Satellites• Idea gained momentum during the Oil

Crises of 1970’s, but after prices stabilized idea was dropped– US Department of Energy research program

1978-1981

ProblemsProblems• Issues identified during the DOE study

– Complexity—30 years to complete– Size—6.5 miles long by 3.3 miles wide

• Transmitting antenna ½ mile in diameter(1 km)

– Cost—$74 billion– Interference

From the SatelliteFrom the Satellite• Solar power from the satellite is sent

to Earth using a microwave transmitter

• Received at a “rectenna” located on Earth

• Recent developments suggest that power could be sent to Earth using a laser

MicrowavesMicrowaves• Frequency 2.45 GHz microwave

beam• Retro directive beam control

capability• Power level is well below international

safety standard

Microwave vs. Laser TransmissionMicrowave vs. Laser Transmission

• Microwave– More developed– High efficiency up

to 85%– Beams is far below

the lethal levels of concentration even for a prolonged exposure

– Cause interference with satellite communication industry

• Laser– Recently

developed solid state lasers allow efficient transfer of power

– Range of 10% to 20% efficiency within a few years

– Conform to limits on eye and skin damage

RectennaRectenna“An antenna comprising a mesh of dipoles

and diodes for absorbing microwave energy from a transmitter and converting it into electric power.”

• Microwaves are received with about 85% efficiency

• Around 5km across (3.1 miles)• 95% of the beam will fall on the

rectenna

5,000 MW Receiving Station (Rectenna). This station is about a

mile and a half long.

5,000 MW Receiving Station (Rectenna). This station is about a

mile and a half long.

2. Theory of Wireless Power Trans. 2. Theory of Wireless Power Trans.

Theory of OperationTheory of Operation

• Electromagnetic Radiation• Antenna basics• Phased-array antenna• Diffraction analogy• Energy distribution• Rectenna• Physical limitations & relationships

Physics of Wireless Power Transmission

Physics of Wireless Power Transmission

• Forms of Electromagnetic radiation

• Travel at same speed• F = frequency• C = velocity of light• L =wavelength• http://imnh.isu.edu/digitalatlas/clima/atmosph/images/waves.jpg

Dipole AntennaDipole Antenna

• Transmission of power is simpler than TV & Radio

• Transmitter: wire half a wavelength

• Pushes electrons back and forth

• Receiver: wire half a wavelength

http://www.zorg.org/radio/dipole_antenna.shtml

Antenna Radiation PatternAntenna Radiation Pattern

http://www.astromag.co.uk/portable/dipole.gif

Phased-array antennaPhased-array antenna• The λs for microwaves

are small dipoles small• Beam focusing: phased-

array antenna• Electronically steered by

varying the timing or phase

• Waves will merge together

http://www.mcs.harris.com/oceannet/features/antenna.html

Phased-Array AntennaPhased-Array Antenna

http://www.cea.com.au/products/phasedarray/i2_ceafar.html

Diffraction analogyDiffraction analogy• Light same properties• Laser beam shinning

trough a narrow opening & spreads out or diffracts

• Bright spot in the center w/fainter spots on the side

http://planetquest.jpl.nasa.gov/technology/diffraction.html

Diffraction & MicrowavesDiffraction & Microwaves

• Waves reinforce at some points and they cancel out at other points (bright and fainter points)

• In microwaves: is a scaled up version of diffraction

IntensityIntensity

Main lobe energyMain lobe energy

• Circular central max• Main lobe• 84% of energy• Sidelobes surround • No energy minima

Intensity 84% in main lobeIntensity 84% in main lobe

RectennaRectenna

• Array of dipole antennas known as rectifying antenna or Rectenna

• Diameter = Dr

RectennaRectenna

Physical LimitationsPhysical Limitations

• The receiving diameter Dr increases with transmitter receiver separation distance S.

• Dr increases if transmitter diameter Dt decreases

Physical LimitationsPhysical Limitations

2. Sample Calculations2. Sample Calculations

Calculations/AnalysisCalculations/Analysis

• Frequency, f (Hz)• Intensity, I (watts per square meter)• Wave-Length, L (meters)• Received Main Beam Lobe (“spot”) Diameter, Dr

(meters or kilometers)• Transmitting Phased Array Diameter, Dt (meters

or kilometers)

• Example: how to estimate Intensity, I ?

Frequency FormulaFrequency Formula

Dt * Dr• Frequency, f (Hz) = --------------

(2)

(L * S)

Dt: transmitting phased array diameter Dr: received main beam lobe (“spot”)

diameter

L: wavelength

S: separation

Frequency AnalysisFrequency Analysis

Dt * DrIf (Frequency, f (Hz) = ----------- ) 2.44 GHz

(2) (L * S)

Then at least, 84% of the energy of the beam will be captured

Note:• This energy is not linear; 42% of the energy is not

equivalent to 1.22 GHz. • Equation (2) represent a best case scenario.• Practical antenna sizes may have to be larger if most of

the beam is to be captured.• The rectenna will have to be at least as large as Dt,

even if (2) says Dr is smaller.

Frequency AnalysisFrequency Analysis

• Such a wide beam can be focused, but only to a minimum size Dr.

• For low Earth-orbit power-beaming demonstrations, it is easier to put the smaller antenna in space and the larger antenna on Earth.

• Early demonstrations may capture only a small percentage of the total power, in order to keep antenna sizes small.– to light up a 60 watt bulb, thousands of watts may have to be

transmitted.– Since costly to launch such a power generating apparatus, the

most feasible demonstration project may be Earth-to-space transmission from a large transmitting antenna (such as the Arecibo dish) to a smaller rectenna in space.

Intensity, I FormulaIntensity, I Formula

• Intensity, I (watts per square meter) P Dt

= ½ ( Pi * -----) * ( --------- ) (3)

4 L * S

Pi: 3.14…P: total power transmittedDt: transmitted phased array diameter L: wave lengthS: transmitter to receiver distance

(separation)

Wave-Length, L CalculationsWave-Length, L Calculations

• Wave-Length, L (meters)

c 300,000,000 meter/sec

= ----- = ( -------------------------------- ) = 0.1224 (1)

f 2,450,000,000/sec meter

c: speed of light

f: frequency

Received Main Beam Lope Diameter, Dr CalculationsReceived Main Beam Lope Diameter, Dr Calculations

• Received Main Beam Lope (“spot”) Diameter, Dr (meters or kilometers) f * L * S 2.44 * 0.12224m * 35,800,000m= -------------- = --------------------------------------------

Dt 1000m

= 10,700 meter = 10.7 kilometers

L: wave lengthS: separationDt: transmitting phased array diameter

Transmitting Phased Array Diameter, Dt CalculationsTransmitting Phased Array Diameter, Dt Calculations

• Transmitting Phased Array Diameter, Dt (meters or kilometers) f * L * S 2.44 * 0.12224m * 35,800,000m= -------------- = ----------------------------------------------

Dr 10,700 meter

= 1000m = 1 kilometers

L: wave lengthS: separationDr: received main beam lope (“spot”) diameter

Example Example

What is the Intensity, I = ?Given: f, Dr, and a typical solar power satellite transmitting 5

billion watts from geostationary orbit 35800 kilometers high.

Solution: Use the following (1), (2), & (3) Cf = ----- L (1) L

Dt * DrFrequency, f (Hz) = -------------- Dt (2)

(L * S) P Dt

Intensity, I (watts/m^²) = ½ ( Pi * -----) * ( --------- ) (3) 4 L * S

Example CalculationsExample Calculations

• Intensity, I (watts per square meter)

P Dt= ½ ( Pi * -----) * ( --------- ) (3)

4 L * S

2287485.869w 1000m= ½ ( Pi * ---------------------------) * ( ----------------------------------- )

4m 0.1224m* 35800,000m

= 205 watts/m^² or 20.5 milliwatts/cm^²

Example AnalysisExample Analysis

• peak beam intensity, Ip = 20.5 milliwatts/cm^² This is about twice US industrial standard for human exposure

This is converted (by rectenna) to electricity by 90% efficiency

• Average intensity, Ia 1/3 * 20.5 milliwatts/cm^²

Rectangular Transmitting antenna array CalculationsRectangular Transmitting antenna array Calculations

• Mathematics slightly different, but the same general principles apply.

• Central maximum of the beam contain 82% of the transmitted energy.

• Rectangular in shape, but will spread out more along TX array’s short direction than its long direction.

• Example: Canada’s Radar satrectangular transmitting antenna: 1.5m × 15m“footprint” on the ground: 7,000m × 50,000mfrequency: 5.3 GHzaltitude: 800,000moutput power: 5000 watts

The power is too spread out at the ground to use in a practical demonstration project.

Two more pointsTwo more points

1. Use certain transmitting methods– to reduce the level of the sidelobes– to put some of the sidelobe energy into the main

lobe– Price to pay: Larger Rectenna (because main

lobe spreads out)

2. Principal of diffraction also limits the resolution of optical systems:– Lenses– Telescopes

3. Major Research Projects 3. Major Research Projects

1979 SPS Reference System concept (GEO)

1979 SPS Reference System concept (GEO)

Accomplishments of Solar Power Satellites

Accomplishments of Solar Power Satellites

• 1980, 30 kW of microwave power was transmitted to a receiving antenna over one mile

• 1993, Japan successfully transmitted a 800W microwave beam from a rocket to a free-flying satellite in space.

• 1998, Microwave to DC conversion efficiency of 82% or higher by the rectenna.

NASA’s 1995-1997 Fresh Look Study NASA’s 1995-1997 Fresh Look Study • MEO (Mid-Earth Orbit)

Sun Tower:

- 6 SPS yields near 24-hr power to sites

- ± 30 degrees Latitude Coverage

- Power services of 200-400 MW

ContinuedContinued

• Solar Disc

- 1 SPS provides nearly 24-hr

power to markets

- Spin-stabilized solar array, de-spun phased array with electronic beam-steering

- Geostationary Earth Orbit

- ± 60 degrees Latitude Coverage

- Power services of about 5 GW

per SPS

-

1999-2000 Space Solar Power (SSP) Exploratory Research and Technology

(SERT) program

1999-2000 Space Solar Power (SSP) Exploratory Research and Technology

(SERT) program• Exploration and Commercial Development

Integral Symmetrical ConcentratorIntegral Symmetrical Concentrator

NASA’s SSP Strategic Research & Technology Roadmaps

NASA’s SSP Strategic Research & Technology Roadmaps

SPS 2000SPS 2000

Details of SPS 2000Details of SPS 2000

• Japan is to build a low cost demonstration of SPS by 2025.

• Eight countries along the equator agreed to be the rectenna sites.

• 10 MW satellite delivering microwave power in the low orbit 1100 km(683 miles)– Will not be in

geosynchronous orbit, instead low orbit 1100 km (683 miles)

– Much cheaper to put a satellite in low orbit

Japan’s Recent Research EffortsJapan’s Recent Research Efforts

• Japan - 2001, Japanese’s Ministry of Economy, Trade and Industry (METI) launched a research program for a solar-powered-generated satellite.

- By 2040, beginning of a SPS operation. The planned satellite will be able to generate 1GW/Sec. (equivalent to the output of a nuclear plant) in a geostationary orbit. The receiving antenna (rectenna) on the ground will be either positioned at desert or sea.

Japan’s Roadmaps for SPS Development

Japan’s Roadmaps for SPS Development

ReferencesReferences• www.on-orbit-servicing.com/pdf/OOS2004_

presentations_pdf/OOSIssuesOverview_Oda.pdf • www.kentlaw.edu/classes/fbosselm/Spring2004/ PowerPoints/Wireless

%20Power%20Transmission%20-%20Soubel.ppt • www.spacefuture.com/.../a_fresh_look_at_space_

solar_power_new_architectures_concepts_and_technologies.shtml • Lin, James C., “Space solar power stations, wireless power transmissions,

and biological implications”, IEEE microwave magazine, March, 2002

4. Comparisons Among Other Power Sources4. Comparisons Among Other Power Sources

Efficiency and CostsEfficiency and Costs

•Space Solar Power (Wireless Power Transmission)•Ground Based Solar Power•Nuclear Energy•Fossil Fuel

Advantages over Earth-based solar powerAdvantages over Earth-based solar power

• More intense sunlight• In geosynchronous orbit, 36,000 km (22,369

miles) an SPS would be illuminated over 99% of the time

• No need for costly storage devices for when the sun is not in view

Cont.Cont.• Waste heat is radiated back into space• Power can be beamed to the location where

it is needed, don’t have to invest in as large a grid

• No air or water pollution is created during generation

• Ground based solar only works during clear days, and must have storage for night. Thus it is More reliable than ground based solar power

Advantages over Nuclear PowerAdvantages over Nuclear Power

There are advantages…• Possible power generation of 5 to 10

gig watts• If the largest conceivable space

power station were built and operated 24 hours a day all year round, it could produce the equivalent output of ten 1 million kilowatt-class nuclear power stations.

Cont…Cont…

• Nuclear power doesn't pollute the atmosphere like fossil fuels. But it does produce waste. This stays radioactive for thousands of years and is very dangerous. At the moment most stations bury their waste deep underground, at sea or send it to other countries. (Britain, for example, accepts and buries nuclear waste from several countries.)

Cont…Cont…• One of the disadvantage of Nuclear• On April 26, 1986 the worst catastrophe in nuclear

history occurred in the station at Chernobyl, Ukraine.• Due to the failure of one of reactor, two people died

immediately from the explosion and 29 from radiation. About 200 others became seriously ill from the radiation; some of them later died. It was estimated that eight years after the  accident 8,000 people had died from diseases due to radiation (about 7,000 of them from the Chernobyl cleanup crew). Doctors think that about 10,000 others will die from cancer. The most frightening fact is that children who were not born when the catastrophe occurred inherited diseases from their parents.

• Source http://oii.org/html/story.html  by Vessela Daskalova

Advantages over Fossil FuelAdvantages over Fossil Fuel

• Fossil fuels won't last forever (next 50yrs)• It is not renewable• The ability to match supply to demand

may already have run out, especially for oil

• Fossil Fuel fired electric power plants in the US emits about 2 billion tons of greenhouse gas CO2 in to air every year. This courses climate change in the future via greenhouse effect.

Cost Cost

• Cost—prototype would have cost $74 billion

• “According to Kyle Datta the Oil Factor,” which predicts that oil could hit $100 a barrel by 2010.

DisadvantagesDisadvantages• If microwave beams carrying power could be

beamed uniformly over the earth. They could power Mobile Devices Eg. cell phones

• Microwave transmission– Interference with other electronic devices– Health and environmental effects

Cont…Cont…• Possible health hazards

– Effects of long term exposure– Exposure is equal to the amount that

people receive from cell phones and Microwaves

• Location– The size of construction for the rectennas

is massive and also Implementation Complexity

Initial conceptual looks at a mega-engineering project as shown in this Boeing design. New technologies point to more efficient, less expensive space solar power systems.

Credit: Boeing/Space Studies Institute

Initial conceptual looks at a mega-engineering project as shown in this Boeing design. New technologies point to more efficient, less expensive space solar power systems.

Credit: Boeing/Space Studies Institute

Early and simple schematic of how a space solar power satellite would beam energy to electrical power grid on Earth. Credit: Space Studies Institute

Early and simple schematic of how a space solar power satellite would beam energy to electrical power grid on Earth. Credit: Space Studies Institute

Sustainable energy Sustainable energy

• To meet the final goal of providing sustainable energy for future growth and protection of the environment, the design and technology for space solar power should be evaluated by the criteria of availability of resources, energy economy (payback time) and waste production such as carbon-dioxide through all the processes required for production of SPS . Power from space should be competitive with other energy sources in this respect. We also need a space solar future if our children are to live in an intact environment. They will be grateful to us

5. Proposed Project/Experiment5. Proposed Project/Experiment

Goal of the ProposalGoal of the Proposal

• Obtain $10,000 grant from EPA to fund our research

Proposed ProjectProposed Project

• Transmit power from AC outlet toa remote circuit wirelessly – to demonstrate the capability of the

technology, – to explore the problems we'll face in a small-

scale experiment, and – to use this experiment as a “probe” to explore

the potential problems of transmitting power from space to earth

BenefitsBenefits

1) For graduate and undergraduate students to research and study about wireless power transmission

2) Demonstration tool for a potential laboratory course

3) Potential commercialization of the proposed project

Block Diagram of Proposed Experiment—1

Block Diagram of Proposed Experiment—1

This is the AC power

supply

AC Power Outlet

Power Conversion

This converts the AC power to

a microwave power signal

Microwave Transmitter

This transmits

the microwave

power signal

Transmitting Side:

Transmitting Side:

Block Diagram of Proposed Experiment—2

Block Diagram of Proposed Experiment—2

Rectenna Power Conversion

PowerRegulator

Remote Device

Receiving Side:

Receiving Side:

This converts the microwave power signal to

DC power signal

This regulates

DC voltage level

Remote Device uses

this DC power the same way

it uses a battery

Vision on Future DevelopmentVision on Future Development

Ability to transmit power

from a

geostationary satellite to a

specific reception site

Ability to transmit power

from a

geostationary satellite to a

specific reception site

Ability to transmit

power from a

local power plant to local

households

Ability to transmit

power from a

local power plant to local

households

Ability to transmit power

within a laboratory

Ability to transmit power

within a laboratory

LocalLocal RegionalRegional Orbital Orbital

6. Conclusion6. Conclusion

ConclusionConclusion

• This idea worth to invest in since this technology brings in virtually unlimited power from the sun.

• This also benefits the intercontinental power providers.

• Absolutely environmentally friendly since it is emission-free.

ReferenceReference1) “A Few Things you occasionally wanted to know about wireless power

transmission.” Potter, Seth. http://www.spacefuture.com/archive/a_few_things_you_occasionally_wanted_to_know_about_wireless_power_transmission.shtml

2) “Solar Power Satellites and Microwave Power Transmission” http://www.kentlaw.edu/classes/fbosselm/Spring2004/PowerPoints/Wireless%20Power%20Transmission%20-%20Soubel.ppt

3) www.on-orbit-servicing.com/pdf/OOS2004_presentations_pdf/OOSIssuesOvervie

w_Oda.pdf

4) www.kentlaw.edu/classes/fbosselm/Spring2004/ PowerPoints/Wireless%20Power%20Transmission%20-%20Soubel.ppt

5) www.spacefuture.com/.../a_fresh_look_at_space_ solar_power_new_architectures_concepts_and_technologies.shtml

6) Lin, James C., “Space solar power stations, wireless power transmissions, and biological implications”, IEEE microwave magazine, March, 2002