Category: Mechanical Seminar Topics

Wireless Battery Charger | Inductively Coupled Universal Battery Charger | Charging Batteries Without Wires | Inductive Power Transfer | Inductive Charging

Wireless Battery Charger based on Inductive Power Transfer

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In the future all electronic devices will be wireless powered. Small, battery-powered gadgets make powerful computing portable. The foundation of wireless charging is the well-known law of Faraday on induced voltage, widely used in motors and transformers.

The wireless battery charger should be capable of charging the most common battery types found in portable  devices today.  In addition, the charging  should be  controlled from the base station and a bidirectional communication system between  the pickups  and base  station  should be developed.

Wireless charging reduces the need for wires to charge tablets, cordless gadgets, and other portable devices. Any battery-powered gadget can be charged with a wireless adapter by simply positioning it near a wireless power transmitter or a dedicated charging station. This makes the unit cabinet still waterproof and can be kept fully sealed. Wireless charging can also significantly improve durability, in addition to the intrinsic ease that it provides, since a charge socket on the side of an appliance can potentially experience technical failure or merely from accidentally plugging an incorrect connector.

Inductive Power Systems based Wireless Battery Charger:

Inductive Power Transfer (IPT)  refers to the concept of transferring electrical power between two isolated circuits across an air gap.  While based on the work and concepts developed by pioneers such as  Faraday and Ampere, it  is  only recently that IPT has been developed into working systems.

Essentially, an IPT system can be divided into two parts;

  • Primary and
  • Secondary.

The primary side of the system is made up of a resonant power supply and a coil. This power supply produces a high frequency sinusoidal current in the coil.  The secondary side (or ‘pickup’) has a smaller coil, and a converter to produce a DC voltage.

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Working of Inductive Power Transfer based Wireless Battery Charger:

In this system communications signals are encoded onto the waveform that provides power to the air gap. Communication from the primary side to the secondary is implemented by switching the power signal at the output of the resonant converter between its normal level  and a lower level which is detectable by the pickup but still provides enough power to control the pickup micro-controller. This process is called Amplitude Shift Keying (ASK). This is achieved by varying the output voltage of the buck converter which provides an input DC voltage to the resonant converter.

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Communication from the secondary to the primary is achieved by a process called Load Shift Keying (LSK).  This involves varying the loading on the pickup.   Any load on the pickup will reflect a voltage on the primary circuit proportional to the load.  Therefore a variation in the load on the pickup can be detected by the charging station.

The communications system must provide two discrete levels of voltage reflected onto the primary side,  to represent the on and off states for digital communications. The difference must be easily detected on the primary side to provide a robust communications channel. Signals are decoded by simple filters and comparators which feed a  digital signal to the micro-controllers.

Wireless Battery charging standards

Several wireless charging protocols are being developed and currently available on the market.

Qi – The Qi wireless charging standard was the first to launch and has since consolidated its dominance. It has been adopted by the big handset maker “Apple,” and it is used by nearly all wireless battery charger for domestic and many other applications. It is effectively an inductive device that transfers power at a comparatively low frequency (between 110 and 205 kHz for low power and 80 to 300 kHz for medium power).

A4WP – A4WP (Alliance for Wireless Power) is a wireless power standard that was established after the Qi standard. It makes use of resonance techniques as well as a higher power transmission frequency of 6.78 MHz for power and 2.4 GHz for control signals. It can also charge several devices at the same time.

Advantages of Wireless Battery Charger:

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IPT has a number of advantages over other power transfer methods  – it is unaffected by dirt, dust, water, or chemicals.  In situations such as coal mining IPT prevents sparks and other hazards.  As the coupling is magnetic, there is no risk of electrocution even when used in high power systems.  This makes IPT very suitable for  transport  systems where vehicles follow a fixed track,  such as  in factory materials handling.

Applications of Wireless Battery Charger

  1. Smart Phones, Tablets and other electronic gadgets – Consumers want simple-to-use solutions, greater positioning versatility, and quicker charging times. Typical power specifications for these applications vary from 2 to 15 watts. Interoperability across different specifications is favoured. NFC (Near Field Communication) and Bluetooth will coexist with wireless charging, making for some innovative solutions. When put back-to-back, paired phones, for example, will charge each other after negotiating the required host and customer.
  2. Accessories of wireless battery charger – Wireless power transfer can benefit headphones, wireless speakers, mouse, keyboards, and a number of other applications. Connecting charging cables to the tiny ports of ever-shrinking computers is a hardware barrier. Bluetooth headsets, for example, must be sweat-proof to survive in a gym environment. This is only possible with wireless charging.
  3. Electric Vehicles with wireless battery charger- Smart charging stations for electric vehicles (EVs) are also on the way, but they’ll need much more energy. The development of norms is ongoing.
  4. Miscellaneous – Wireless battery chargers are working their way through anything that has a battery. Remote controllers for video games and televisions, cordless power tools, cordless vacuum cleaners, soap dispensers, hearing aids, and even cardiac pacemakers fell under this category. Wireless battery chargers may also be used to charge super capacitors or some other system that uses a low-voltage power cord.

Graphene | Graphene Technology | Graphene The Material Of The Future | Graphene Review | How Will Graphene Properties Be In The Future | 5 Secrets That Experts Of Graphene Production Don’t Want You To Know

Graphene  the  Material  of  the  Future

01-graphene-a ultra thin material-graphene extraction from graphite-tracing graphene from graphite-graphite_pencil The graphene is a substance which has a single-layer crystal lattice of carbon atoms, which is unusual since it is different from all of the materials of its kind. Several researchers have identified a way of making this substance, which allows them to use it in various fields and especially for the high-speed electronic devices.

If the 20th century was the age of plastics, the 21st century seems set to become the age of graphene—a recently discovered material made from honeycomb sheets of carbon just one atom thick.

People are discovering and inventing new materials all the time, but we seldom hear about them because they’re often not that interesting. Graphene was first discovered in 2004, but what’s caused such excitement is that its properties (the way it behaves as a material) are remarkable and exciting. Briefly, it’s super-strong and stiff, amazingly thin, almost completely transparent, extremely light, and an amazing conductor of electricity and heat. It also has some extremely unusual electronic properties.

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Graphene Definition:

Graphene is defined as a one atom thin sheet of carbon atoms arranged in a Hexagonal format or a flat monolayer of carbon atoms that are tightly packed into a 2D honeycomb lattice.

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History of Graphene:

In October 2010, two University of Manchester (U.K.) scientists, Andre Geim and Konstantin Novolselov, were awarded the 2010 Nobel Prize in physics for their research on graphene. Graphene is a one-atom-thick sheet of carbon whose strength, flexibility, and electrical conductivity have opened up new horizons for high-energy particle physics research and electronic, optical, and energy applications.

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Graphene properties:

Graphene oxide, a single-atomic-layered material made by reacting graphite powders with strong oxidizing agents, has the ability to easily convert into graphene a low-cost carbon-based transparent and flexible electronics.

Graphene Oxide:

Graphene oxide has been known in the scientific world for more than a century and was largely described as hydrophilic, or attracted to water. These graphene oxide sheets behave like surfactants, the chemicals in soap and shampoo that make stains disperse in water.

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Mechanical Properties of Graphene:

Graphene is the thinnest material known to man at one atom thick, and also incredibly strong – about 200 times stronger than steel. On top of that, graphene is an excellent conductor of heat and electricity and has interesting light absorption abilities. It is truly a material that could change the world, with unlimited potential for integration in almost any industry.

Young’s Modulus:

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1. Graphene sheets stack to form graphite with an interplanar spacing of 0.335 nm, which means that a stack of 3 million sheets would be only one millimeter thick.

2. Graphene is a Zero Gap Semiconductor. So it has a high electron mobility at room temperature. It’s a Superconductor. Electron transfer is 100 times faster then Silicon.

3. Graphene has a record breaking strength of 200 times greater than steel, with a tensile strength of 130GPa.

4. Graphene can be used to create circuits that are almost superconducting, potentially speeding electronic components by as much as 1000 times.

5. Graphene electrodes used in lithium-ion batteries could reduce recharge times from two hours to about 10 minutes.

Graphene Production:

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Chemical Vapor Deposition (CVD) and Molecular Beam Epitaxy (MBE) are two other potential routes to Graphene growth. Graphene is indeed very exciting, but producing high quality materials is still a challenge. Dozens of companies around the world are producing different types and grades of graphene materials – ranging from high quality single-layer graphene synthesized using a CVD-based process to graphene flakes produced from graphite in large volumes.

High-end graphene sheets are mostly used in R&D activities or in extreme applications such as sensors, but graphene flakes, produced in large volumes and at lower prices, are adopted in many applications such as sports equipment, consumer electronics, automotive and more.

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Applications of Graphene Technology:

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