wirless power transmission
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Wireless power transmission involves transferring electrical energy from a power source to devices without wires. There are two main techniques: near-field uses induction or resonance within short distances, while far-field like microwave or laser transmission requires line-of-sight but can transmit over longer distances. Wireless power has advantages of no wires or maintenance but challenges of tuning and safety. Applications include wireless charging of devices and electric vehicles, as well as potential large-scale power from solar satellites.
wirless power transmission
- 2. DEFINITION • As the word wireless means “without wire”. • Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electric load without interconnecting man made conductors. • Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous or impossible.
- 3. Why WPT? • Reliable • Efficient • Fast • Low maintenance cost • Can be used for short-range or long- range. 2/12/2015 Wireless Power Transmission 3
- 4. History Sir NICOLAI TESLA was the first one to propose and research the idea of wireless transmission in 1899, since than many scholars and scientists have been working to make his dream a reality • His vision for “World Wireless System” • The 187 feet tall tower to broadcast energy • All people can have access to free energy • Due to shortage of funds, tower did not operate 2/12/2015 Wireless Power Transmission 4
- 5. History (contd…) • Tesla was able to transfer energy from one coil to another coil • He managed to light 200 lamps from a distance of 40km • The idea of Tesla is taken in to research after 100 years by a team led by Marin Soljačić from MIT. The project is named as ‘WiTricity’. 2/12/2015 Wireless Power Transmission 5
- 6. Types and Technologies of WPT • Near-field techniques Inductive Coupling Resonant Inductive Coupling Air Ionization • Far-field techniques Microwave Power Transmission (MPT) LASER power transmission 2/12/2015 Wireless Power Transmission 6
- 7. Inductive coupling • Primary and secondary coils are not connected with wires. • Energy transfer is due to Mutual Induction 2/12/2015 Wireless Power Transmission 7
- 8. Inductive coupling (contd…) • Transformer is also an example • Energy transfer devices are usually air-cored • Wireless Charging Pad(WCP),electric brushes are some examples • On a WCP, the devices are to be kept, battery will be automatically charged. 2/12/2015 Wireless Power Transmission 8
- 9. Inductive coupling(contd…) • Electric brush also charges using inductive coupling • The charging pad (primary coil) and the device(secondary coil) have to be kept very near to each other • It is preferred because it is comfortable. • Less use of wires • Shock proof 2/12/2015 Wireless Power Transmission 9
- 10. Resonance Inductive Coupling(RIC) • Combination of inductive coupling and resonance • Resonance makes two objects interact very strongly • Inductance induces current 2/12/2015 Wireless Power Transmission 10
- 11. Block diagram of RIC 2/12/2015 Wireless Power Transmission 11 This type of oscillation is resonance if the reactance's of the inductor and capacitor are equal
- 12. WiTricity 2/12/2015 Wireless Power Transmission 12 Based on resonance inductive coupling Energy transfer wirelessly for a distance just more than 2m. Used frequencies are 1MHz and 10MHz
- 13. An example 2/12/2015 Wireless Power Transmission 13
- 14. Air Ionization • Toughest technique under near-field energy transfer techniques • Air ionizes only when there is a high field • Needed field is 2.11MV/m • Natural example: Lightening • Not feasible for practical implementation 2/12/2015 Wireless Power Transmission 14
- 15. Advantages of near-field techniques • No wires • No e-waste • Need for battery is eliminated • Efficient energy transfer using RIC • Harmless, if field strengths under safety levels • Maintenance cost is less 2/12/2015 Wireless Power Transmission 15
- 16. Disadvantages • Distance constraint • Field strengths have to be under safety levels • Initial cost is high • In RIC, tuning is difficult • High frequency signals must be the supply • Air ionization technique is not feasible 2/12/2015 Wireless Power Transmission 16
- 17. Far-field energy transfer • Radiative • Needs line-of-sight • LASER or microwave • Aims at high power transfer • Tesla’s tower was built for this 2/12/2015 Wireless Power Transmission 17
- 18. Microwave Power Transfer(MPT) • Transfers high power from one place to another. Two places being in line of sight usually • Steps: – Electrical energy to microwave energy – Capturing microwaves using rectenna – Microwave energy to electrical energy 2/12/2015 Wireless Power Transmission 18
- 19. MP T (contd…) • AC can not be directly converted to microwave energy • AC is converted to DC first • DC is converted to microwaves using magnetron • Transmitted waves are received at rectenna which rectifies, gives DC as the output • DC is converted back to AC 2/12/2015 Wireless Power Transmission 19
- 20. LASER transmission • LASER is highly directional, coherent • Not dispersed for very long • But, gets attenuated when it propagates through atmosphere • Simple receiver – Photovoltaic cell • Cost-efficient 2/12/2015 Wireless Power Transmission 20
- 22. Solar Power Satellites (SPS) • To provide energy to earth’s increasing energy need • To efficiently make use of renewable energy i.e., solar energy • SPS are placed in geostationary orbits 2/12/2015 Wireless Power Transmission 22
- 23. SPS (contd…) • Solar energy is captured using photocells • Each SPS may have 400 million photocells • Transmitted to earth in the form of microwaves/LASER • Using rectenna/photovoltaic cell, the energy is converted to electrical energy • Efficiency exceeds 95% if microwave is used. 2/12/2015 Wireless Power Transmission 23
- 25. Rectenna
- 26. Rectenna in US • Rectenna in US receives 5000MW of power from SPS and about one and a half mile long. 2/12/2015 Wireless Power Transmission 26
- 27. Advantages of far-field energy transfer • Efficient • Easy • Need for grids, substations etc are eliminated • Low maintenance cost • More effective when the transmitting and receiving points are along a line-of-sight • Can reach the places which are remote 2/12/2015 Wireless Power Transmission 27
- 28. Disadvantages of far-field energy trasnfer • Radiative • Needs line-of-sight • Initial cost is high • When LASERs are used, – conversion is inefficient – Absorption loss is high • When microwaves are used, – interference may arise 2/12/2015 Wireless Power Transmission 28
- 29. Applications • Near-field energy transfer – Electric automobile charging • Static and moving – Consumer electronics – Industrial purposes • Far-field energy transfer – Solar Power Satellites – Energy to remote areas – Can broadcast energy globally (in future) 2/12/2015 Wireless Power Transmission 29
- 31. Conclusion • Transmission without wires- a reality • Efficient • Low maintenance cost. But, high initial cost • Better than conventional wired transfer • Energy crisis can be decreased • Low loss • In near future, world will be completely wireless