sixth blog

Imagine a future in which wireless power transfer is feasible: cell phones, household robots, mp3 players, laptop computers and other portable electronics capable of charging themselves without ever being plugged in, freeing us from that final, ubiquitous power wire. Some of these devices might not even need their bulky batteries to operate.
Ventures of transmitting power wirelessly have been accomplished for centuries and have been carried by many of them. Perhaps the best known example is electromagnetic radiation, such as radio waves. While such radiation is excellent for wireless transmission of information, it is not feasible to use it for power transmission. Since radiation spreads in all directions, a vast majority of power would end up being wasted into free space. One can envision using directed electromagnetic radiation, such as lasers, but this is not very practical and can even be dangerous. It requires an uninterrupted line of sight between the source and the device, as well as a sophisticated tracking mechanism when the device is mobile.
Wireless energy transfer or wireless power transmission is the process that takes place in any system where electrical energy is transmitted from a power source to an electrical load, without interconnecting wires in an electrical grid. Wireless transmission is ideal in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible. With wireless energy transfer, the efficiency is a more critical parameter and this creates important differences in these technologies.
When two Magnetically Resonating objects at “Strongly coupled” regime tend to exchange energy efficiently by transfer of power in the non-radiating fields. This is the basic principle involved in it. By taking two coils having same magnetic resonance and one is coupled to source and other is coupled to Device. So that the energy transfer is efficient even the air gap between them is high.
This paper describes the basic history of wireless power transmission, what are Magnetic resonance and strongly coupled regime, Experimental design, Range and rate of coupling (coupling calculations) and Design of parameters and Simulation for variation of power with and without the external object between source and load

INTRODUCTION:

Witricity is based upon coupled resonant objects to transfer energy between objects without wires. The system consists of a Witricity transmitter, and devices which act as receivers.

The action of an electrical transformer is the simplest instance of wireless energy transfer. The primary and secondary circuits of a transformer are not directly connected. The transfer of energy takes place by electromagnetic coupling through a process known as mutual induction. (An added benefit is the capability to step the primary voltage either up or down.) The battery charger of an electric toothbrush is an example of how this principle can be used. The main drawback to induction, however, is the short range. The receiver must be very close to the transmitter or induction unit in order to inductively couple with each other.

History of Wireless power:

Wireless power transmission is not new for us. Various methods of Transmitting power wirelessly have been known for centuries. In 1899, Sir Nikola Tesla proposed a method to transmit energy over long distances wirelessly using Electromagnetic radiation principle, but such radiation is excellent for wireless transmission of Information, it is not feasible to Power transmission. Since radiation spreads in all directions, a vast majority of power would end up being wasted into free space. So radioactive modes of Omni directional antennas are not suitable for the Power transfer.

Directed radiation modes like Lasers or highly-directional antennas can be efficiently used for energy transfer even for long distances but require existence of an uninterruptible line-of-sight and a complicated tracking system in the case of mobile objects and also not Eco friendly. So these procedures are insufficient to Wireless power transmission.

There is another new procedure called “WITRICITY--Wireless Electricity” which is for Midrange energy transfer. This method is mainly based on the transmission of magnetic energy by taking two Magnetically Resonant objects in Strongly Coupled regime. The source and load are coupled to the coils which are magnetically resonant and transmit energy in the magnetic form in strongly coupled regime. Because they are magnetic resonance, there