SURVEY OF WIRELESS POWER TRANSFER TECHNIQUES IN CHARGING MOBILE DEVICES

ABSTRACT Wireless power transmission is the transmission of electrical energy from one point to another without using any conductor or wire through vacuum or atmosphere. It is useful to transfer electrical energy to those places where it is hard to transmit energy using conventional wires. The advent of various wireless technologies have revolutionized the communication infrastructure and consequently changed the entire world into a global village. Use of wireless technology has also been made for transmission of electric power wirelessly. It can reduce heavy line losses; increase the portability of power systems. It also integrates the communication technologies and electric power to the same platform. This paper presents comprehensive review and detailed analysis of various techniques used for wireless power transmission. Role of wireless power transmission in charging mobile devices, distance of each of techniques charging mobile devices has also been covered, theory of each techniques and how they works, data are presented for power transfer efficiency of both receivers. Graphs are given to show the comparison of power and efficiency with distance of both receivers.

KEYWORDS: Wireless Power Transfer, Magnetic Resonant Coupling, Quality Factor, witricity, electromagnetic field, magnetic field(flux), Electromagnetic field:  electric and magnetic field together are referred to as electromagnetic field. Magnetic field (flux): The area around a magnet within which magnetic force is exerted. This result from the flow of current through wires or electrical charges and increases in strength as the current increases. Magnetic field is only produced when current is flowing. Witricity: wireless electricity system   TABLE OF CONTENT TITLE PAGE ABSTRACT
TABLE OF CONTENT 1.0INTRODUCTION                        2.0INDUCTION AND MAGNETIC RESONANT COUPLING 2.1INDUCTION COUPLING 2.2MAGNETIC RESONANT COUPLING         3.0MICROWAVE POWER TRANSFER 3.1DRAWBACK OF MICROWAVE POWER TRANSFER 4.0WI-CHARGE POWER BEAM TECHNOLOGY 5.0COMPARISM OF WIRELESS POWER TRANSFER 6.0ADVANTAGE, DISADVANTAGE AND APPLICATION 7.0CONCLUSION 8.0REFERENCES   INTRODUCTION Role of electricity in modern machine era is considered like circulation of blood in human body. Electrical energy has made human life easy and luxurious. Electricity is being distributed using the conventional grid which is in service for last hundred years. Conventional grid is characterized by out dated infrastructure, delayed communication and heavy transmission losses. One of the solutions of the heavy line losses is the transmission of electricity wirelessly which is called Witricity.      Goal of wireless power transmission is to transfer electricity from source to destination in order to reduce high transmission losses. Wireless power transmission increases the portability and convenience. It also fulfils the demand of recent devices and technologies which already use wireless technique for different operations and communications like Wi-Fi being used in laptops and cellular phones for the access to the internet. Transfer of electric power without using wires is possible.    Nicola Tesla is the pioneer of the wireless power transmission concept and he implemented his concept in 1902 with the technologies available at that time. Since then, many of the scientists involved in further extension of this idea and achieved positive results for the transmission at a close range [1]. In 2007, a team at the Massachusetts Institute of Technology (MIT), was successful in transferring the power wirelessly at a mid-range using magnetic coupling resonance by lighting a bulb 0f 60w at a range of 2m . Smart grid is the concept of modernizing the conventional grid by integration of advanced digital communications. Wireless communications will play an important role for realization of smart grid. Witricity also helps in achieving the goals of 21st century power quality requirements and special applications. Electrical vehicles are supposed to replace the conventional internal combustion engines in smart grid. Wireless charging for mobile devices  is an important application of Witricity.