30-07-2011, 04:24 PM
wireless power transmission. slides.ppt (Size: 2.27 MB / Downloads: 255)
Introduction :
History:
Principle :
Electro Dynamic Induction Effect
The "electrodynamic inductive effect" or "resonant inductive coupling" has key implications in solving the main problem associated with non-resonant “Inductive Coupling”.. This is where the resonance comes in and helps efficiency dramatically by "tunneling“. the magnetic field to a receiver coil that resonates at the same frequency. If resonant coupling is used, where inductors are tuned to a mutual frequency and the input current is modified from a sinusoidal into a nonsinusoidal rectangular or transient waveform.
Ex : Microphone , wireless Mic etc. . .
Wireless Mic Set
Microwave Power Transmission:
Power transmission via Micro waves can be made more directional, allowing longer distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A Rectenna may be used to convert the microwave energy back into electricity. Rectenna conversion efficiencies exceeding 95% have been realized. Power beaming using microwaves has been proposed for the transmission of energy from orbiting solar power satellites to Earth and the beaming of power to spacecraft leaving orbit has been considered
NASA Fresh Look Report:
SSP could be competitive with other energy sources and deserves further study
Research aimed at an SSP system of 250 MW
Would cost around $10 billion and take 20 years
National Research Council found the research worthwhile but under funded to achieve its goals
How the Power gets to Earth :
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
Frequency 2.45 GHz microwave beam
Retro directive beam control capability
Power level is well below international safety standard
Rectenna:
“An Rectenna comprising a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converting it into electric power.”
Lasers :
In the case of electromagnetic radiation closer to visible region of spectrum (10s of microns (um) to 10s of nm), power can be transmitted by converting electricity into a laser beam that is then pointed at a solar cell receiver. This mechanism is generally known as "powerbeaming" because the power is beamed at a receiver that can convert it to usable electrical energy.