1. SOLAR POWER SATELLITE AND MICROWAVE WIRELESS POWER TRANSMISSION TECHNOLOGY

2. CONTENTS INTRODUCTION WHY SPS SPS-THE BACKGROUND SPS-GENERAL IDEA
WIRELESS POWER TRASMISSION
MICROWAVE POWER TRASMISSION IN SPS
TRANSMITTER
BEAM CONTROL
RECTENNA
ADVANTAGES
APPLICATIONS

3. INTRODUCTION
The new millennium has introduced increased pressure for finding new renewable energy sources.
Building a power station in space to transmit electricity to Earth by way of radio waves-the Solar Power Satellites.
Microwave Wireless Power Transmission.
SPS is a clean, large-scale, stable electric power source.

4. WHY SPS ? Increasing global energy demand.
Limitation of renewable energy sources.
Environmental problems due to fossil fuels.
Overcome day & night effect and other factors such as clouds.
Overcome energy crisis.

5. SPS– THE BACKGROUND Peter Glaser invented the concept of a large SPS.
The U.S Department of Energy (DOE) and the
National Aeronautics and Space Administration
(NASA) examined the SPS concept extensively
during the late 1970s.
Fresh look Study, SPS Concept Definition Study.
SPS Exploratory and Research Technology.

6. SPS- A GENERAL IDEA It is located in the geosynchronous orbit.
Comparison between ordinary satellite.
Its operation.
About structure.
Comparison between terrestrial station.

8. WIRELESS POWER TRANSMISSION
The 50Hz ac power tapped from grid line is stepped down to suitable voltage level for rectification in to dc.
Then it is supplied to oscillator fed magnetron.
Magnetron consist of electrons supplied by cathode which are collected by positively charged anode.
The electrons are forced to move in a circular path by a high power permanent magnet.
Electromagnetic radiation in microwave range is generated

9. MICROWAVE TRANSMISSION IN SPS
The conversion of direct power to microwave power.
The formation and control of microwave beam.
The collection of the microwave energy and its conversion into electrical energy at the earth’s surface.
The key microwave components in a WPT system are the transmitter, beam control and the receiving antenna called RECTENNA .

10. TRANSMITTER
The key requirement of a transmitter is its ability to convert dc power to RF power efficiently and radiate the power to a controlled manner with low loss.
The transmitter’s efficiency drives the end-to-end efficiency as well as thermal management system.
The main components of a transmitter include dc-to-RF converter and transmitting antenna.
The main dc-RF converter s are klystrons.

11. BEAM CONTROL
A key system and safety aspect of WPT in its ability to control the power beam.
Retro directive beam control systems have been the preferred method of achieving accurate beam pointing.
A coded pilot signal is emitted from the rectenna towards the SPS transmitter to provide a phase reference for forming and pointing the power beams.

12. RETRO DIRECTIVE BEAM CONTROL

13. RECTENNA Rectenna is the microwave to dc converting device .
It is mainly composed of a receiving antenna and a rectifying circuit.
Fig. shows schematic of Rectenna. It consists of a receiving antenna, an input low pass filter, a rectifying circuit and an output smoothing filter.
In Rectenna arrays, the diode is the most critical component to achieve higher efficiencies because it is the main source of loss.
Diode cut off frequency is given by ƒ=1/ [2πRsCj], where ƒ is the cut off frequency, Rs is the diode series resistance, Cj is the zero-bias junction capacitance.

14. SCHEMATIC OF RECTENNA CIRCUIT

15. ADVANTAGES
The power could be directed to any point on the earth’s surface.
The power density would be uninterrupted by darkness, clouds, or precipitation, which are the problems encountered with earth based solar arrays.
The realization of the SPS concept holds great promises for solving energy crisis
No moving parts.
No fuel required.
No waste product.

16. APPLICATIONS
Solar power satellite (SPS) is the largest application of the WPT.
The SPS concept arose because space has several major advantages over earth for the collection of solar power.
There is no air in space, so the satellites would receive somewhat more intense sunlight, unaffected by weather.
Another application of the WPT is moving targets such as fuel free airplanes, fuel free electric vehicles, moving robots and fuel free rockets.
Microwave devices offer the highest efficiency of conversion between DC electricity and microwave radiative power.

17. REFERENCES
[1] Hiroshi Matsumoto, “Research on solar power satellites and microwave power transmission in Japan”, IEEE microwave magazine, pp.36-45, Dec
2002.
[2] James O. Mcspadden & John C. Mankins,”Space solar power programs and microwave wireless power transmission technology”, IEEE microwave magazine, pp.46-57, Dec 2002.
[3] J.C. Mankins,”A fresh look at space solar power: new architectures, concepts and technologies” in 38th Astronautical Federation.
[4] Seth Potter, “Solar power satellites: an idea whose time has come [online] Available on last updated on Dec.1998.
[5] Consumer Energy Information: EREC Reference Briefs [online] Available

19. M.Aruna mytrayee & M.Lakshmi iswarya
FROM
M.Aruna mytrayee
&
M.Lakshmi iswarya

20. THANK YOU……