INTRODUCTION

 
Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electrical load without a conductive physical connection. Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous, or impossible. The problem of wireless power transmission differs from that of wireless telecommunications, such as radio. In the latter, the proportion of energy received becomes critical only if it is too low for the signal to be distinguished from the background noise. With wireless power, efficiency is the more significant parameter.  A large part of the energy sent out by the generating plant must arrive at the receiver or receivers to make the system economical. The most common form of wireless power transmission is carried out using direct induction followed by resonant magnetic induction. Other methods under consideration include electromagnetic radiation in the form of microwaves or lasers.

Inductive coupling

In electrical engineering, two conductors are referred to as mutual-inductively coupled or magnetically coupled when they are configured such that change in current flow through one wire induces a voltage across the ends of the other wire through electromagnetic induction. The amount of inductive coupling between two conductors is measured by their mutual inductance. The coupling between two wires can be increased by winding them into coils and placing them close together on a common axis, so the magnetic field of one coil passes through the other coil. The two coils may be physically contained in a single unit, as in the primary and secondary sides of a transformer, or may be separated. Coupling may be intentional or unintentional. Unintentional coupling is called cross-talk, and is a form of electromagnetic interference. Inductive coupling favors low frequency energy sources. High frequency energy sources generally use capacitive coupling. An inductively coupled transponder comprises an electronic data carrying device, usually a single microchip, and a large coil that functions as an antenna. Inductively coupled transponders are almost always operated passively.

Devices that use inductive coupling include:

• Transformers
• Electric motors and generators
• Induction loop communication systems
• Metal detectors
• Graphics tablet
• Radio Frequency Identification
• Electronic article surveillance tags to prevent theft (most types).
• Inductive Modems
• Resonant energy transfer
• Inductive charging products charge batteries using inductive coupling, such as eCoupled; Torches, Cochlear Implants and many electric toothbrushes.
• Induction cookers and induction heating systems

 As for final year project my group already pick this kind of theoretical method for our next semester project. there is several kind of methods for the wireless power transmission can be done. But i choose the Inductive Coupling Method for the project. We use this method to charge mobile phone via wireless.

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