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wireless power transfer project

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Wireless Power Transfer

Wireless Power Transfer

1. INTRODUCTION

Wireless power transmission (WPT) is an efficient way for the transmission of electric power from one point to another through vacuum or atmosphere without the use of wire or any substance. By using WPT, power can be transmitted using inductive coupling for short range,resonant induction for mid-range and Electromagnetic wave power transfer. By using this technology, it is possible to supply power to places, which is hard to do using conventional wires. Currently, the use of inductive coupling is in development and research phases. The most common wireless power transfer technologies are the electromagnetic induction and the microwave power transfer.

For efficient midrange power transfer, the wireless power transfer system must satisfy three conditions: (a) high efficiency, (b) large air gap, (c) high power. The microwave power transfer has a low efficiency. For near field power transfer this method may be inefficient, since it involves radiation of electromagnetic waves. Wireless power transfer can be done via electric field coupling, but electric field coupling provides an inductively loaded electrical dipole that is an open capacitor or dielectric disk. Extraneous objects may provide a relatively strong influence on electric field coupling. Magnetic field coupling may be preferred, since extraneous objects in a magnetic field have the same magnetic properties as empty space. Electromagnetic induction method has short range.

Since magnetic field coupling is a non-radioactive power transfer method, it has higher efficiency. However, power transfer range can be increased by applying magnetic coupling with resonance phenomenon applied on. A magnetic field is generated when electric charge moves through space or within an electrical conductor. The geometric shapes of the magnetic flux lines produced by moving charge (electric current) are similar to the shapes of the flux lines in an electrostatic field. Inductive or magnetic coupling works on the principle of electromagnetism. When a wire is proximity to a magnetic field, it induces a magnetic field in that wire. Transferring energy between wires through magnetic fields is inductive coupling

1.1 LITERATURE SURVEY 1. January 2013 by Corresponding author: Sadegh Vaez-Zadeh ([email protected]).

According to the World Resources Institute (WRI), India`s electricity grid has the highest transmission and distribution losses in the world a whopping 27%. Numbers published by various Indian government agencies put that number at 30%, 40% and greater than 40%. This is attributed to technical losses (grid`s inefficiencies) and theft. Any problem can be solved by state of -the-art technology. The above discussed problem can be solved by choosing an alternative option for power transmission which could provide much higher Efficiency; low transmissions cost and avoid power theft. Microwave Power Transmission is one of the promising Technologies and may be the righteous alternative for efficient power transmission.2. January 2014 by Corresponding author: Ada S. Y. Poon (S98M04) the B.Eng. and M.Phil. degrees in electrical and electronic engineering from the University of Hong Kong.

The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated. This loss implies that our present system of electrical distribution is only 70-74% efficient. We have to think of alternate state - of - art technology to transmit and distribute the electricity. Now- a- days global scenario has changed a lot and there are tremendous development in every field. If we don`t keep pace with the development of new power technology we have to face a decreasing trend in the development of power sector. The transmission of power without wires may be one noble alternative for electricity transmission. Projections of future energy needs over this new century show an increase by a factor of at least two and half, perhaps by as much as a factor of five. All of the scenarios indicate continuing use of fossil sources, nuclear, and large hydro. However, the greatest increases come from new renewable and all scenarios show extensive use of these sources by 2050. Indeed, the projections indicate that the amount of energy derived from new renewable by 2050 will exceed that presently provided by oil and gas combined. This would imply a major change in the world`s energy infrastructure.

2. METHODOLOGY

1. W. P. T. works on the principle of mutual induction between the two coils.2. There are two copper coils arranged one at the sender end and other at the receiver end .The first coil is attached to the power source while the second coil to the light bulb.3. When the power is switched on the first coil converts the electricity into magnetic field, which is oscillating at a particular frequency i.e, AC source.4. The second coil at the receiver end converts the magnetic field into electricity .The surrounding environment is unaffected.

Projecting magnetic field Transmitting Coil Receiving Coil

3. BLOCK DIAGRAM

Fig: Block diagram of proposed method

3.1 WORKING

Progressing from left to right on the top line of the diagram, the input power to the system is usually either wall power (AC mains) which is converted to DC in an AC/DC rectifier block, or alternatively, a DC voltage directly from a battery or other DC supply. In high power applications a power factor correction stage may also be included in this block. A high efficiency switching amplifier converts the DC voltage into an RF voltage waveform used to drive the source resonator.

Often an impedance matching network (IMN) is used to efficiently couple the amplifier output to the source resonator while enabling efficient switching-amplifier operation. Class D or E switching amplifiers are suitable in many applications and generally require inductive load impedance for highest efficiency. The IMN serves to transform the source resonator impedance, loaded by the coupling to the device resonator and output load, into such impedance for the source amplifier.

The magnetic field generated by the source resonator couples to the device resonator, exciting the resonator and causing energy to build up in it. This energy is coupled out of the device resonator to do useful work, for example, directly powering a load or charging a battery. A second IMN may be used here to efficiently couple energy from the resonator to the load. It may transform the actual load impedance into effective load impedance seen by the device resonator which more closely matches the loading for optimum efficiency.

For loads requiring a DC voltage, a rectifier converts the received AC power back into DC. In the earliest work at MIT, the impedance matching was accomplished by inductively coupling into the source resonator and out of the device resonator. This approach provides a way to tune the input coupling, and therefore the input impedance, by adjusting the alignment between the source input coupling coil and the source resonator, and similarly, a way to tune the output coupling, and therefore the output impedance, by adjusting the alignment between the device output coupling coil and the device resonator.

With proper adjustment of the coupling values, it was possible to achieve power transfer efficiencies approaching the optimum possible efficiency (Equation 6). Figure 2 shows a schematic representation of an inductive coupling approach to impedance matching. In this circuit g M is adjusted to properly load the source resonator with the generators output resistance. The device resonator is similarly loaded by adjusting L M , the mutual coupling to the load. Series capacitors may be needed in the input and output coupling coils to improve efficiency unless the reactance of the coupling inductors is much less than the generator and load resistances.

It is also possible to directly connect the generator and load to the respective resonators with variety of IMNs. These generally comprise components (capacitors and inductors) that are arranged in T and/or pi configurations. The values of these components may be chosen for optimum efficiency at a particular source-to-device coupling and load condition (fixed tuned impedance matching) or they may be adjustable to provide higher performance over a range of source-to-device positions and load conditions (tuneable impedance matching). The requirements of the particular application will determine which approach is most appropriate from a performance and cost perspective.

4. SOFTWARE & HARDWARE REQUIRMENTS1. Computer for designing system.2. No of Coils for Transmission as well as Receiver.3. Transformer, Capacitors, Diodes, Regulator IC`s.4. Transistors, LED, Fan, CFLs, Adapters5. SMPS

5. FLOW CHART

WPT model

TestingDesign elevationSystem designElectric modellingMagnetic modellingSystem analysisPower supply design

6. ADVANTAGES 1. An advantage is that we can produce electricity anywhere without wires2. The power can be delivered in any direction i.e. Omni directional3. Most common things in our surroundings do not interact with these magnetic fields and thus not harmful to other living beings. 4. No need for meter rooms and electrical closets. 5. Reduction of e-waste by eliminating the need for power cords6. Need more light in your office, no need for electrician

6.1 DISADVANTAGES

1. The flux condition should satisfy certain conditions; if not no power supply takes place.2. There is a loss of power transmission if there is a strong Ferro-magnetic substance.3. Need for standardization and adaptation. So no overheating occurs because of different voltages.4. Retrofitting old equipment or purchasing new equipment could become a very expensive endeavour.

7. APPLICATIONS

Wirelessly power and operate an LCD

Wirelessly charge a battery in a smart phone

Instead of having a separate charger for each mobile phone in your family, you can have a charging surface that handles all of them at once. This flexibility opens the application space as well as makes systems easier and more convenient to use. A single source can be used to transfer energy to more than one device, even when the devices have different power requirements.

7.2 Medical Applications

Power provided to medical LVAD with help of WPT

WPT used in pacemaker

Wireless charging systems are being developed for implanted medical devices including LVAD heart assist pumps, pacemakers, and infusion pumps. Using highly resonant wireless power transfer, such devices can be efficiently powered through the skin and over distances much greater than the thickness of the skin, so that power can be supplied to devices deeply implanted within the human body.

7.3 Electric Vehicles

Electric charger placed in parking zone of electric car

WPT for charging full electric and hybrid vehicles

Wireless charging systems are being developed for rechargeable hybrid and battery electric vehicles. These systems already deliver 3.3 kW at high efficiency over a distance of 10 cm -20 cm (typical vehicle ground clearances). Figure shows the Audi Urban Concept Vehicle, demonstrated by Audi. It is expected that wireless charging will vastly improve the charging experience for EV owners, making such vehicles even more attractive to consumers.

7.4 Home Applications

LED lights directly powered by highly resonant wireless Energy transfer systems.

LED (light emitting diode) lights can be directly powered with wireless electricity, eliminatingThe need for batteries in under-cabinet task lighting, and enabling architectural lighting designers to create products that seemingly float in mid-air, with no power cord. The LED fixture shown in the left photo in Figure 8 is powered by a 10 W source mounted above the ceiling, and using two resonant repeaters (the white disks) to improve the efficiency of the Energy transfer.

8. SAFTY

1. Any living organisms that are placed in between the two coils(transmitter & receiver) will not halt or hinder the transmission of magnetic field.2. It is because the magnetic rays will not interact with the living tissues so strong and can be easily passed through the humans or other living organisms. 3. The purposes of the IEEE [10] and ICNIRP [11] guidelines are similar:4. The main objective of this publication is to establish guidelines for limiting EMF (electromagnetic field) exposure that will provide protection against known adverse health effects. An adverse health effect causes a detectable impairment of the health of the exposed individual or of his or her offspring; a biological effect on the other hand, may or may not result in an adverse health effect. [ICNIRP]5. The purpose of this standard is to provide exposure limits to protect against established adverse health effects to human health induced by exposure to RF (radio frequency) electric, magnetic, and electromagnetic fields over the frequency range of 3 kHz to 300GHz.[IEEE]

9. CONCLUSION

1. A wireless power transfer system capable of transferring the required amount of power without wire to various devices.2. Reduces complexity of wired network.3. This concept offers greater possibilities for transmitting power with negligible losses and ease of transmission.2)

10. REFERENCES

1. Received 22 October 2012, Accepted 25 January 2013, Scheduled 28 January 2013Corresponding author: Sadegh Vaez-Zadeh ([email protected]) IEEE,2013

2. A.B. Kurs, A. Karalis, R. Moffatt, J.D. Joannopoulos, P.H. Fisher, and M. Soljacic, Wireless Power Transfer via Strongly Coupled Magnetic Resonances, IEEE Transactions, pp. 83- 86,(2014).http://www.ieee.org.

3. A. Karalis, J.D. Joannopoulos, and M. Soljacic, Efficient Wireless Non-radiative Midrange Energy Transfer, Ann. Phys., 323, pp. 34-48, (2008); published IEEE online April 2010.

4. William C. Brown, The history of power transmission by radio waves, Microwave Theory and Techniques, IEEE Transactions, 32(9):1230-1242, September 2011

5. Nicola Tesla, The transmission of electrical energy without wires, Electrical World and Engineer, March 1905. http://www.tfcbooks.com/tesla/1904-03-05.htm, (acc. Dec. 08).

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PVPIT Budhgaon [E&TC Department]Page 17