Conceptual basics necessary to study wireless power transmission(WPT)
Its been a long time since I posted the previous blog where the necessity of wireless power transmission was discussed as in the aspect of smart India . In this blog the conceptual basics needed to study the WPT are explained at an very easy level so that people other than technical backgrounds can also understand.
1. Electricity
2. Magnetism
3. Mutual Induction
4. Resonance
5. Microwave radiation
6. Laser beam technology
1. Electricity - In simple language electricity is a “ flow of charge”. To understand this the basic physics is required. The discussion has to be then transferred to the structure of atom. Atom is invisible to us with the naked eyes, many atoms combine to make a molecule, which builds the matter which one can physically see and touch. Atom is made up of 3 different particles the protons , neutrons and electrons. Atom has a central nucleus where it consists of protons and neutrons. Protons have positive charge and neutrons have neutral charge. The orbiting particles in an atom are known as electrons .They carry negative charge. For the flow of charge we need the charge carriers. These electrons and protons help us in that matter. The electrons in the outer orbit of an atom are known as the valence electrons. When the outside force is strong enough , a valence electron can escape orbit of the atom and become free. Free electrons allow us to move charge, which is known as electricity.
2. Magnetism- Magnetism is a property of a material to attract or repel other material. For e.g. magnets attract material having iron in it and does not attracts material having aluminum,steel,plastic etc in it. Magnets can be of two types - permanent magnet or electro magnet. Permanent magnet is a material having magnetic property by nature, while electromagnet is prepared by winding a electric wire on a normal iron piece and when the electricity passes through it , it acts as an electromagnet. Every magnet has its own area only in which it can attract the objects. This is known as a magnetic field. The force of attraction or repulsion in between the two magnets depends upon their poles. Every magnet has 2 poles i.e. north pole and the south pole. The two opposite poles attract each other and the same poles repel each other. Magnetism is caused due to the alignment of electrons in a specific manner.
3. Mutual Induction – The power from one circuit can be transferred to another circuit without any physical connection between them , but the circuits must be magnetically coupled. This concept is known as mutual induction. This is used only for power transfer and not for power generation. To study mutual induction , consider two circuits , a primary circuit and a secondary circuit. The primary circuit is connected to mains and produces its own flux. This flux circulates in magnetic core and gets linked with the secondary circuit. According to the Faraday’s law of electromagnetism an electromotive force gets induced in the circuit due to the linked flux . This is a technique used for short range power transfer between two circuits. Not all the flux gets linked from one circuit to another , some of it does not link and it is known as the leakage flux.
4. Resonance – Resonance means a vibration caused in an object due to vibration effect in another object. Firstly one should know that every object has its own frequency , and when due to any vibration / movement if the frequency of two objects matches with each other , then they start to vibrate at abnormal frequency. This frequency is known as resonant frequency. Resonance is of two types – 1) Series resonance and 2) Parallel resonance .When the inductive reactance and the capacitive reactance becomes equal Resonance is said to happen. For wireless power transmission resonant inductive coupling and resonant magnetic coupling techniques are utilized.
5. Microwave radiation - Micro means extremely small and wave means movement and radiation means energy emission, so in simple words microwave radiation means movement of extremely small energy emissions. In a microwave radiation the transmitter transmits the signal which is then received by the receiver at other end. The transmitter and receiver needs to stay in line of sight for the transfer. The detailed study of microwave radiation will be posted in the upcoming posts.
6. Laser beam technology - A laser is an abbreviation for ‘Light Amplification by Stimulated Emission of Radiation’. It is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Laser are distinguished from other light sources by their spatial coherence. Spatial coherence allows a laser to stay narrow over great distances enabling applications such as laser pointers.The output of the laser is hence diffraction limited. Laser beams can be focused to very tiny spots, achieving a very high radiance so that they can have very low divergence in order to concentrate their power at a single point.
