# Tutorial on Wireless electricity transmission basics

This page of tutorials section covers low range Wireless electricity transmission basics.It mentions electromagnetic and resonance magnetic coupling methods used in wireless electricity transmission.

As we know electricity is necessity of human life. It is difficult to pass a single day without electricity. Before we move into wireless electricity let us understand some of the core terminologies and basic concepts associated with the subject.
Electricity: In simple terms, flow of electrons through conductor wire or flow of charges through atmosphere is known as electricity.
Magnetism : In nature, certain materials attract or repel each other such as magnets used in refrigerator and earth's magnetic field. These are objects having constant magnetic fields. Time varying oscillating magnetic fields are generated using flow of AC current on wire. Moreover flow of electric current through wire generates magnetic field wrapped around the wire.
Electromagnetism : The term is used to denote both electric and magnetic field. Oscillating magnetic field produces electric field and oscillating electric field produces magnetic field.
Magnetic Induction: A loop or coil made of conductive material carrying AC(alternating current) is used to generate and to capture magnetic field. It is a very efficient structure used for magnetic induction.
Energy or power coupling : The coupling of energy or power occurs when one object has means to transfer energy to the other object.
Resonance : It is basically property of physical systems. It can also be thought as natural frequency at which energy can be efficiently added to the oscillating system/module. The value of resonant frequency depends on size, shape and thickess of material. The classic example is child swinging in a swing.

## Wireless Electricity Technology Overview

The figure-1 depicts basic principle of wireless electricity. It works based on principle of using coupled resonant objects in order to transfer electricity without the use of wires.

This system composed of DC/AC inverter, split transformer, transmitting inductor, receiving inductor, rectifier with filter and linear voltage regulation circuit. Both the base unit and portable device unit are connected using magnetic induction as shown which passes energy between them.

## How does wireless electricity transmission Work?

Let us understand how wireless electricity transmission works for shorter distances. If one conductive loop is interfaced and powered with AC source, it will produce oscillating magnetic field around the loop of wire(i.e. coil). The other conducting loop kept near to the first will capture portion of oscillating magnetic field. This results into generation or induction of electric current in the secondary coil. This generation of coil will be used to power the electric or electronic devices. The concept is similar to the electric transformer. The receiver should be in range with the transmitter for the system to work efficiently.

• As shown in the fig-2 circuit-A converts 60Hz current to 10 MHz and feeds the same to transmitting coil B.

•  Oscillating current inside the transmitting coil will cause coil to emit 10MHz magnetic field.

•  The receiving coil resonates at the frequency used by transmitting coil. This process is called magnetic induction. It picks up energy from coil-B's magnetic field.

• The energy of oscillating magnetic field will induce current in the receiving coil(C). Hence the bulb(D) will be lighted as shown.

## Advantages and applications of wireless electricity

• It is more convenient, more reliable and more environment friendly
• It is used in low, full and high power product categories.
• It is used for industrial applications such as mining, robotics, drilling, packaging machinery etc.
• It is used in MRI machines to produce diagnostic images of soft tissue based on magnetic resonance imaging principle.