Methods of wireless transmission of electricity. New wireless power technology works like Wi-Fi

Wireless electricity has become known since 1831, when Michael Faraday discovered the phenomenon of electromagnetic induction. He experimentally established that a changing magnetic field generated by an electric current can induce electric current in another conductor. Numerous experiments were carried out, thanks to which the first electrical transformer. However, only Nikola Tesla managed to fully translate the idea of transmitting electricity over a distance into practical application.

At the Chicago World's Fair in 1893, he demonstrated the wireless transmission of electricity by lighting phosphorus bulbs that were spaced apart. Tesla demonstrated many variations on the transmission of electricity without wires, dreaming that in the future this technology would allow people to transmit energy in the atmosphere to long distances. But at this time this invention of the scientist turned out to be unclaimed. Only a century later did people become interested in Nikola Tesla’s technologies Intel and Sony, and then other companies.

How does this work

Wireless electricity literally represents transmission electrical energy without wires. This technology is often compared to the transmission of information, such as Wi-Fi, cell phones and radios. Wireless electricity– this is a relatively new and dynamic emerging technology. Today, methods are being developed to safely and efficiently transmit energy over a distance without interruption.

The technology is based on magnetism and electromagnetism and is based on a number of simple operating principles. First of all, this concerns the presence of two coils in the system.

The system consists of a transmitter and a receiver, which together generate an alternating magnetic field of variable current.
This field creates voltage in the receiver coil, for example, to charge a battery or power a mobile device.
When electric current is sent through a wire, a circular magnetic field appears around the cable.
On a coil of wire that is not receiving electric current directly, electric current will begin to flow from the first coil through the magnetic field, including the second coil, providing inductive coupling.

Transfer principles

Until recently, the magnetic resonance system CMRS, created in 2007 at the Massachusetts Institute of Technology, was considered the most advanced technology for transmitting electricity. This technology provided current transmission over a distance of up to 2.1 meters. However, some limitations prevented it from being put into mass production, for example, high transmission frequency, large sizes, complex coil configuration, as well as high sensitivity to external interference, including human presence.

However, scientists from South Korea have created a new electricity transmitter that will transmit energy up to 5 meters. And all devices in the room will be powered by a single hub. The resonant system of DCRS dipole coils is capable of operating up to 5 meters. The system does not have a number of disadvantages of CMRS, including the use of fairly compact coils measuring 10x20x300 cm, which can be discreetly installed in the walls of an apartment.

The experiment made it possible to transmit at a frequency of 20 kHz:

209 W at 5 m;
471 W at 4 m;
1403 W at 3 m.

Wireless electricity allows you to power modern large LCD TVs, which require 40 W, at a distance of 5 meters. The only thing that will be “pumped out” from the electrical network is 400 watts, but there will be no wires. Electromagnetic induction provides high efficiency, but at a short distance.

There are other technologies that allow you to transmit electricity wirelessly. The most promising of them are:

Laser radiation . Provides network security as well as greater range. However, line of sight between the receiver and transmitter is required. Working installations using laser beam power have already been created. Lockheed Martin, an American manufacturer of military equipment and aircraft, tested the Stalker unmanned aerial vehicle, which is powered by a laser beam and remains in the air for 48 hours.
Microwave radiation . Provides a long range, but has a high equipment cost. A radio antenna is used as a transmitter of electricity, which creates microwave radiation. The receiver device has a rectenna, which converts the received microwave radiation into electric current.

This technology makes it possible to significantly distance the receiver from the transmitter, and there is no direct need for line of sight. But as the range increases, the cost and size of the equipment increases proportionally. At the same time, high-power microwave radiation generated by the installation can be harmful to the environment.

Peculiarities

The most realistic of the technologies is wireless electricity based on electromagnetic induction. But there are limitations. Work is underway to scale the technology, but health safety issues arise here.
Technologies for transmitting electricity using ultrasound, laser and microwave radiation will also develop and will also find their niches.
Orbiting satellites with huge solar panels need a different approach, targeted transmission of electricity will be required. Laser and microwave are appropriate here. On at the moment No perfect solution, however, there are many options with their pros and cons.
Currently, major telecommunications equipment manufacturers have joined together to form the Wireless Electromagnetic Energy Consortium to create a worldwide standard for wireless chargers that operate on the principle of electromagnetic induction. Of the major manufacturers, support for the QI standard on a number of their models is provided by Sony, Samsung, Nokia, Motorola Mobility, LG Electronics, Huawei, and HTC. Soon QI will become a single standard for any similar devices. Thanks to this, it will be possible to create wireless charging zones for gadgets in cafes, transport hubs and other public places.

Application

Microwave helicopter. The helicopter model had a rectenna and rose to a height of 15 m.
Wireless electricity is used to power electric toothbrushes. The toothbrush has a completely sealed body and has no connectors, which avoids electric shock.
Powering aircraft using lasers.
Wireless charging systems for mobile devices that can be used every day have become available on sale. They work on the basis of electromagnetic induction.
Universal charging pad. They allow you to power most popular smartphone models that are not equipped with a wireless charging module, including regular phones. In addition to the charging pad itself, you will need to buy a receiver case for the gadget. It connects to a smartphone via a USB port and is charged through it.
Currently, over 150 devices up to 5 Watts that support the QI standard are sold on the world market. Equipment will appear in the future medium power up to 120 Watt.

Prospects

Today we are working on large projects, which will use wireless electricity. This is power supply for electric vehicles “over the air” and household electrical networks:

A dense network of car charging points will make it possible to reduce batteries and significantly reduce the cost of electric vehicles.
Power supplies will be installed in each room, which will transmit electricity to audio and video equipment, gadgets and household appliances equipped with appropriate adapters.

Advantages and disadvantages

Wireless electricity has the following advantages:

No power supplies required.
Complete absence of wires.
Eliminate the need for batteries.
Less maintenance required.
Huge prospects.

Disadvantages also include:

Insufficient technology development.
Limited by distance.
Magnetic fields are not completely safe for humans.
High cost of equipment.

When Apple company introduced its first wireless charger for cell phones and gadgets, many considered it a revolution and a huge leap forward in wireless energy transfer methods.

But were they pioneers, or even before them, did someone manage to do something similar, albeit without proper marketing and PR? It turns out there were, and a very long time ago, and there were many such inventors.

So back in 1893, the famous Nikola Tesla demonstrated the glow of fluorescent lamps to the amazed public. Despite the fact that they were all wireless.

Now any schoolchild can repeat this trick by going out into an open field and standing with a lamp. daylight under the line high voltage from 220kv and above.

A little later, Tesla managed to light the same wirelessly phosphorus incandescent light bulb.

In Russia in 1895, A. Popov showed the world's first radio receiver in operation. But by and large, this is also a wireless transfer of energy.

The most important question and at the same time the problem of the entire technology of wireless charging and similar methods lies in two points:

how far can electricity be transmitted this way?

and what quantity

First, let's figure out what power the devices and household appliances around us have. For example, a phone, smartwatch or tablet requires a maximum of 10-12W.

The laptop already has higher demands - 60-80W. This can be compared to the average incandescent light bulb. But household appliances, especially kitchen appliances, already consume several thousand watts.

Therefore, it is very important not to skimp on the number of outlets in the kitchen.

So what methods and methods for transmitting electrical energy without the use of cables or any other conductors has mankind come up with over all these years? And most importantly, why are they still not implemented as actively into our lives as we would like?

Take the same kitchen appliances. Let's take a closer look.

Transferring energy through coils

The most easily implemented method is to use inductors.

The principle here is very simple. Take 2 coils and place them close to each other. One of them is supplied with power. The other plays the role of receiver.

When the current in the power source is adjusted or changed, the magnetic flux in the second coil automatically changes as well. As the laws of physics say, in this case an EMF will arise and it will directly depend on the rate of change of this flow.

It would seem that everything is simple. But the shortcomings spoil the whole rosy picture. Three disadvantages:

low power

Using this method, you will not transfer large volumes and will not be able to connect powerful devices. If you try to do this, you will simply melt all the windings.

short distance

Don't even think about transmitting electricity over tens or hundreds of meters here. This method has limited effect.

To physically understand how bad things are, take two magnets and figure out how far apart they need to be before they stop attracting or repelling each other. The efficiency of coils is approximately the same.

You can, of course, get creative and ensure that these two elements are always close to each other. For example, an electric car and a special charging road.

But how much will the construction of such highways cost?

low efficiency

Another problem is low efficiency. It does not exceed 40%. It turns out that you will not be able to transmit a lot of electrical energy over long distances in this way.

The same N. Tesla pointed out this back in 1899. Later, he switched to experiments with atmospheric electricity, hoping to find a clue and solution to the problem in it.

However, no matter how useless all these things may seem, with their help you can still organize beautiful light and music performances.

Or recharge equipment much larger than phones. For example electric bicycles.

Laser energy transfer

But how can more energy be transmitted over a greater distance? Think about which films we see this kind of technology very often.

The first thing that comes to mind even for a schoolchild is Star Wars, lasers and lightsabers.

Of course, with their help you can convey large number electricity over very long distances. But again everything is spoiled by a small problem.

Fortunately for us, but unfortunately for the laser, the Earth has an atmosphere. And it just does a good job of jamming and eating up most of the total energy of laser radiation. Therefore, with this technology we need to go into space.

There have also been attempts and experiments on Earth to test the functionality of the method. Nasa even held a competition on laser wireless energy transfer with a prize fund of just under $1 million.

In the end, Laser Motive won. Their winning result is 1 km and 0.5 kW of transmitted continuous power. However, during the transfer process, scientists lost 90% of all the original energy.

But still, even with an efficiency of ten percent, the result was considered successful.

Let us remember that a simple light bulb has even less useful energy that goes directly into the light. Therefore, it is profitable to make infrared heaters from them.

Microwave

Is there really no other really working way to transmit electricity without wires? There is, and it was invented even before attempts and children's games in star wars.

It turns out that special microwaves with a length of 12 cm (frequency 2.45 GHz) are transparent to the atmosphere and it does not interfere with their propagation.

No matter how bad the weather, when transmitting using microwaves, you will only lose five percent! But to do this, you must first convert electric current into microwaves, then catch them and return them to their original state.

Scientists solved the first problem a long time ago. They invented a special device for this and called it a magnetron.

Moreover, this was done so professionally and safely that today each of you has such a device at home. Go into the kitchen and take a look at your microwave.

It has the same magnetron inside with an efficiency of 95%.

But how to do the reverse transformation? And here two approaches were developed:

American

Soviet

In the USA, back in the sixties, scientist W. Brown came up with an antenna that performed the required task. That is, it converted the radiation incident on it back into electric current.

He even gave it his own name - rectenna.

After the invention, experiments followed. And in 1975, with the help of a rectenna, as much as 30 kW of power was transmitted and received at a distance of more than one kilometer. Transmission losses were only 18%.

Almost half a century later, no one has been able to surpass this experience. It would seem that the method has been found, so why weren’t these rectennas released to the masses?

And here again the shortcomings emerge. Rectennas were assembled using miniature semiconductors. Normal operation for them it is the transfer of only a few watts of power.

And if you want to transfer tens or hundreds of kW, then get ready to assemble giant panels.

And this is where unsolvable difficulties arise. Firstly, this is re-emission.

Not only will you lose some energy because of it, but you will also not be able to get closer to the panels without losing your health.

The second headache is the instability of semiconductors in the panels. It is enough for one to burn out due to a small overload, and the rest fail like an avalanche, like matches.

In the USSR everything was somewhat different. It was not for nothing that our military was confident that even in the event of a nuclear explosion, all foreign equipment would immediately fail, but Soviet equipment would not. The whole secret is in the lamps.

At Moscow State University, two of our scientists, V. Savin and V. Vanke, designed the so-called cyclotron energy converter. It has decent dimensions, as it is assembled based on lamp technology.

Externally, it is something like a tube 40 cm long and 15 cm in diameter. The efficiency of this lamp unit is slightly less than that of the American semiconductor thing - up to 85%.

But unlike semiconductor detectors, a cyclotron energy converter has a number of significant advantages:

reliability

high power

overload resistance

no re-emission

low manufacturing cost

However, despite all of the above, semiconductor methods of project implementation are considered advanced all over the world. There is also an element of fashion here.

After the first appearance of semiconductors, everyone abruptly began to abandon tube technologies. But practical tests suggest that this is often the wrong approach.

Of course, lamp cell phones 20 kg each or computers that occupy entire rooms are of no interest to anyone.

But sometimes only proven old methods can help us out in hopeless situations.

As a result, today we have three opportunities to transmit energy wirelessly. The very first one discussed is limited by both distance and power.

But this is quite enough to charge the battery of a smartphone, tablet or something larger. The efficiency, although small, is still a working method.

The first of them started out very encouragingly. In the 2000s, on Reunion Island, a need arose for the constant transmission of 10 kW of power over a distance of 1 km.

The mountainous terrain and local vegetation did not allow laying any air lines power transmission or cable.

All movements on the island to this point were carried out exclusively by helicopters.

To solve the problem, the best minds from different countries were gathered into one team. Including those previously mentioned in the article, our scientists from Moscow State University V. Vanke and V. Savin.

However, at the moment when the practical implementation and construction of energy transmitters and receivers should have begun, the project was frozen and stopped. And with the onset of the crisis in 2008, they completely abandoned it.

In fact, this is very disappointing, since the theoretical work done there was colossal and worthy of implementation.

The second project looks crazier than the first. However, real funds are allocated for it. The idea itself was expressed back in 1968 by US physicist P. Glaser.

He proposed a not entirely normal idea at that time - to bring to geostationary orbit a huge satellite 36,000 km above the earth. Place solar panels on it that will collect free energy from the sun.

Then all this should be converted into a beam of microwave waves and transmitted to the ground.

A sort of “death star” in our earthly realities.

On the ground, the beam must be caught by giant antennas and converted into electricity.

How big do these antennas need to be? Imagine that if the satellite is 1 km in diameter, then the receiver on the ground should be 5 times larger - 5 km (the size of the Garden Ring).

But size is only a small part of the problem. After all the calculations, it turned out that such a satellite would generate electricity with a capacity of 5 GW. When reaching the ground there would be only 2GW left. For example, the Krasnoyarsk hydroelectric power station produces 6 GW.

Therefore, his idea was considered, calculated and put aside, since everything initially came down to price. The cost of the space project in those days reached $1 trillion.

But science, fortunately, does not stand still. Technologies are improving and becoming cheaper. Several countries are already developing such a solar space station. Although at the beginning of the twentieth century for wireless transmission There was only enough electricity for one brilliant person.

The total price of the project dropped from the original to $25 billion. The question remains - will we see its implementation in the near future?

Unfortunately, no one will give you a clear answer. Bets are placed only on the second half of this century. Therefore, for now, let's be content with wireless chargers for smartphones and hope that scientists will be able to increase their efficiency. Well, or in the end, a second Nikola Tesla will be born on Earth.

Ecology of consumption. Technologies: Scientists at the American Disney Research Laboratory have developed a wireless charging method that makes wires and chargers.

Today's smartphones, tablets, laptops and other portable devices have enormous power and performance. But, in addition to all the advantages of mobile electronics, it also has reverse side– constant need to recharge via wires. Despite all the new battery technology, this necessity reduces the convenience of devices and limits their movement.

Scientists at the American Disney Research Laboratory have found a solution to this problem. They developed a wireless charging method that made wires and chargers unnecessary. Moreover, their method allows you to simultaneously charge not only gadgets, but also, for example, household appliances and lighting.

"Our innovative method makes electric current as ubiquitous as Wi-Fi,” says Alanson Sample, one of the laboratory’s directors and its leading scientist. “It opens the way for further developments in robotics, previously limited by battery capacity. So far we have demonstrated the operation of the installation in a small room, but there are no obstacles to increasing its capacity to the size of a warehouse.”

A system for wireless transmission of electricity was developed back in the 1890s by the famous scientist Nikola Tesla, but the invention did not receive mass distribution. Today's wireless power transmission systems operate mainly in extremely confined spaces.

The method, called quasistatic cavity resonance (QSCR), involves applying current to the walls, floor and ceiling of a room. They, in turn, generate magnetic fields that act on a receiver containing a coil connected to the device being charged. The electricity generated in this way is transferred to the battery, having previously passed through capacitors that exclude the influence of other fields.

Tests have shown that in this way up to 1.9 kilowatts of power can be transmitted through a regular electrical network. This energy is enough to simultaneously charge up to 320 smartphones. Moreover, according to scientists, such technology is not expensive and its commercial production can be easily established.

The tests took place in a room specially created from aluminum structures measuring 5 by 5 meters. Sample emphasized that metal walls may not be necessary in the future. It will be possible to use conductive panels or special paint.

The developers claim that their method of transmitting energy through the air does not pose any threat to human health or any other living beings. Their safety is ensured by discrete capacitors that act as an insulator against potentially dangerous electric fields. published

Scientists have been studying the issue of transmitting electricity without wires for the third century. IN lately It’s not that the question has not lost its relevance, but rather has taken a step forward, which is only pleasing. We decided to tell readers of the site in detail how wireless transmission of electricity over distances has developed from the beginning to the present day, as well as what technologies are already in practice.

History of development

The transmission of electricity over a distance without wires develops hand in hand with progress in the field of radio transmission, because the principle of operation in these phenomena is in many ways similar, if not the same. Most inventions are based on the method of electromagnetic induction, as well as electrostatic fields.

In 1820 A.M. Ampere discovered the law of interaction of currents, which was that if a current flows in two closely located conductors in the same direction, then they are attracted to each other, and if in different conductors, they repel.

M. Faraday in 1831 established in the process of conducting experiments that an alternating (changing in magnitude and direction over time) magnetic field generated by the flow of electric current induces currents in nearby conductors. Those. Electricity is transmitted wirelessly. We discussed this in detail in the article earlier.

Well, J.C. Maxwell, 33 years later, in 1864, translated Faraday’s experimental data into mathematical form; Maxwell’s equations themselves are fundamental in electrodynamics. They describe how electric current and electromagnetic field are related.

The existence of electromagnetic waves was confirmed in 1888 by G. Hertz, during his experiments with a spark transmitter with a chopper on a Ruhmkorff coil. In this way, EM waves with frequencies of up to half a gigahertz were produced. It is worth noting that these waves could be received by several receivers, but they must be tuned in resonance with the transmitter. The radius of the installation was around 3 meters. When a spark occurred in the transmitter, the same occurred at the receivers. In fact, these are the first experiments in transmitting electricity without wires.

In-depth research was carried out by the famous scientist Nikola Tesla. In 1891 he studied AC high voltage and frequency. As a result, the following conclusions were drawn:

For each specific purpose, you need to configure the installation to the appropriate frequency and voltage. However, high frequency is not a prerequisite. Best results was achieved at a frequency of 15-20 kHz and a transmitter voltage of 20 kV. To obtain a current of high frequency and voltage, an oscillatory discharge of a capacitor was used. In this way, it is possible to transmit both electricity and produce light.

At his speeches and lectures, the scientist demonstrated the glow of lamps (vacuum tubes) under the influence of a high-frequency electrostatic field. Actually, Tesla’s main conclusions were that even if resonant systems are used, it will not be possible to transfer a lot of energy using an electromagnetic wave.

In parallel, a number of scientists were engaged in similar research until 1897: Jagdish Bose in India, Alexander Popov in Russia and Guglielmo Marconi in Italy.

Each of them contributed to the development of wireless power transmission:

J. Boche in 1894, ignited gunpowder, transmitting electricity over a distance without wires. He did this at a demonstration in Calcutta.
A. Popov transmitted the first message using Morse code on April 25 (May 7), 1895. In Russia, this day, May 7, is still Radio Day.
In 1896, G. Marconi in Great Britain also transmitted a radio signal (Morse code) over a distance of 1.5 km, later 3 km on Salisbury Plain.

It is worth noting that Tesla’s work, underestimated in its time and lost for centuries, was superior in parameters and capabilities to the work of his contemporaries. At the same time, namely in 1896, his devices transmitted signals over long distances (48 km), unfortunately this was a small amount of electricity.

And by 1899 Tesla came to the conclusion:

The inconsistency of the induction method seems enormous in comparison with the method of exciting the charge of the earth and air.

These findings would lead to other research; in 1900, he managed to power a lamp from a coil placed in a field, and in 1903, the Wondercliffe Tower on Long Island was launched. It consisted of a transformer with a grounded secondary winding, and on top of it stood a copper spherical dome. With its help, it was possible to light 200 50-watt lamps. At the same time, the transmitter was located 40 km from it. Unfortunately, these studies were interrupted, funding was stopped, and free transmission of electricity without wires was not economically profitable for businessmen. The tower was destroyed in 1917.

These days

Wireless power transmission technologies have made great strides, mainly in the field of data transmission. Thus, radio communications have achieved significant success, wireless technologies such as Bluetooth and Wi-fi. There were no special innovations, mainly the frequencies and signal encryption methods changed, the signal presentation moved from analog to digital form.

If we are talking about transmitting electricity without wires to power electrical equipment, it is worth mentioning that in 2007, researchers from the Massachusetts Institute transmitted energy 2 meters and lit a 60-watt light bulb in this way. This technology is called WiTricity, it is based on electromagnetic resonance of the receiver and transmitter. It is worth noting that the receiver receives about 40-45% of the electricity. A general diagram of a device for transmitting energy through a magnetic field is shown in the figure below:

The video shows an example of using this technology to charge an electric vehicle. The idea is that a receiver is attached to the bottom of the electric vehicle, and a transmitter is installed on the floor in a garage or other place.

You must position the car so that the receiver is positioned above the transmitter. The device transmits quite a lot of electricity wirelessly - from 3.6 to 11 kW per hour.

In the future, the company is considering providing electricity with such technology and household appliances, as well as the entire apartment as a whole. In 2010, Haier introduced wireless tv, which receives power using similar technology as well as video signals wirelessly. Similar developments are being carried out by other leading companies such as Intel and Sony.

Wireless power transmission technologies are widespread in everyday life, for example, for charging a smartphone. The principle is similar - there is a transmitter, there is a receiver, the efficiency is about 50%, i.e. To charge with a current of 1A, the transmitter will consume 2A. The transmitter in such kits is usually called the base, and the part that connects to the phone is called the receiver or antenna.

Another niche is the wireless transmission of electricity using microwaves or lasers. This provides a greater range than the couple of meters provided by magnetic induction. In the microwave method, a rectenna (a nonlinear antenna for converting an electromagnetic wave into D.C.), and the transmitter directs its radiation in this direction. In this version of wireless transmission of electricity, there is no need for direct visibility of objects. The downside is that microwave radiation is not safe for the environment.

In conclusion, I would like to note that wireless transmission of electricity is certainly convenient for use in everyday life, but it has its pros and cons. If we talk about using such technologies to charge gadgets, the advantage is that you do not have to constantly insert and remove the plug from the connector of your smartphone, and therefore the connector will not fail. The downside is the low efficiency; if for a smartphone energy losses are not significant (several watts), then for wireless charging of an electric car this is a very big problem. The main goal of development in this technology is to increase the efficiency of the installation, because against the background of the widespread race for energy saving, the use of technologies with low efficiency is very doubtful.

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Eating in an intangible way household appliances, freed from electrical wires, have excited the minds of inventors not for the first time. But now experts have come to the point of teaching commercial vacuum cleaners, floor lamps, televisions, cars, implants, mobile robots and laptops to effectively and safely receive current from a wireless source.

Recently, a team of scientists from the Massachusetts Institute of Technology (MIT), led by Marin Soljačic, took another step towards turning wireless electricity technology from a laboratory “trick” into a replicable technology. Quite unexpectedly, they discovered an effect that allows them to increase transmission efficiency. But before talking about the new experiment, it’s worth making a digression.

As a carrier of energy in in this case a near magnetic field is used, oscillating with high frequency several megahertz. For transfer, two magnetic coils are needed, tuned to the same resonance frequency. Scientists compare the transfer of energy between them to the destruction of a resonating glass glass when it “hears” a sound of a strictly defined frequency.

Idealized (in this figure) magnetic coils (yellow), surrounded by their fields (red and blue), transfer energy to each other at a distance D, many times greater than the size of the coils themselves. This is what scientists call resonant magnetic coupling (or coupling) - Resonant Magnetic Coupling (illustration by WiTricity).

As a result of the interaction of the coils, what has been called “Wireless Electricity” (WiTricity) is obtained. By the way, this word is - trademark, which belongs to the corporation of the same name, founded by Soljachich and a number of his colleagues from MIT. The Corporation indicates that this term applies only to its technology and to products created based on it. We kindly ask you not to use “whitecity” as a synonym for wireless energy transmission in general.

The inventors also ask not to confuse WiTricity with the transfer of energy via electromagnetic waves: they say, new method- “non-emitting”.

And a few more important “nots” indicated by the creators. WiTricity is not an analogue of a transformer with windings separated by several meters (the latter in this case stops working). This is not an improved electric toothbrush: although it can be charged without electrical contact, it still requires placement in a “dock” to bring the transmitting and receiving inductive coils closer to a distance of a millimeter. "Whitecity" is not a microwave that can fry a living object, since the pulsating magnetic field operating in the WiTricity system does not affect a person. Finally, “Wireless Electricity” is not even Tesla’s “mysterious and terrible” Wardenclyffe Tower, with which the great inventor intended to demonstrate the transmission of energy over long distances.

The first experiment in wireless energy transfer using the WiTricity method to a 60-watt light bulb, more than two meters away from the source, was carried out by Marin and his colleagues in 2007. The efficiency was low - about 40%, but even then the inventors pointed to a tangible advantage of the new product - safety.

The field used in the system is 10 thousand times weaker than what reigns in the core of the magnetic resonance imaging scanner. So neither living organisms, nor medical implants, nor pacemakers and other sensitive equipment of this kind, nor consumer electronics can feel the effect of this field.

WiTricity's main authors: Marin Solyacic (left), Aristeidis Karalis and John Joannopoulos. Right: circuit diagram WiTricity. The transmitting coil (left) is plugged into the socket. Reception - connected to the consumer. Lines magnetic field the first coil (blue) are able to bend around relatively small conductive obstacles (and they do not even notice wood, fabric, glass, concrete or a person), successfully transferring energy (yellow lines) to the receiving ring (photo MIT/Donna Coveney, illustration WiTricity) .

Now Soljachich and his associates have discovered that the efficiency of the WiTricity system is influenced not only by the size, geometry and tuning of the coils, as well as the distance between them, but also by the number of consumers. Paradoxical at first glance, however, two receiving devices placed at a distance of 1.6 to 2.7 meters on either side of the transmitting “antenna” showed 10% better efficiency than if communication was carried out only between one source and consumer, as was the case in previous experiments.

Moreover, the improvement was observed regardless of what the efficiency was for the transmitter-receiver pairs separately. Scientists have suggested that with the further addition of new consumers, the efficiency will further increase, although it is not yet entirely clear how much. (Details of the experiment are revealed in Applied Physics Letters.)

The transmitting coil in the new experiment had an area of 1 square meter, and the receiving coils were only 0.07 m 2 each. And this is also interesting: the bulkiness of the “receivers” in previous experiments called into question the desire of equipment manufacturers to equip their equipment with such systems - you would hardly like a self-charging laptop, the WiTricity unit of which is comparable in size to the computer itself.

Left: 1 - a special circuit converts ordinary alternating current into high-frequency current, it powers a transmitting coil that creates an oscillating magnetic field. 2 – the receiving coil in the consumer device must be tuned to the same frequency. 3 – the resonant connection between the coils turns the magnetic field back into electric current, which powers the light bulb.
Right: According to the authors of the system, one coil in the ceiling can supply energy to all appliances and devices in the room - from several lamps and a TV to a laptop and DVD player (illustration by WiTricity).

But the main thing is that the effect of improving overall efficiency while working with several consumers at the same time means a green light for Soljachich’s blue dream - a house filled with a variety of equipment receiving power from invisible “non-emitting emitters” hidden in the ceilings or walls of rooms.

Or maybe not only in the rooms, but also in the garage? Of course, you can charge an electric car in the usual way. But the beauty of WiTricity is that you don’t need to connect anything anywhere or even remember about it - theoretically, the car itself can be taught upon arrival at the garage (or company parking lot) to send a “request” to the system and recharge the battery from a magnetic coil placed in the floor.

By the way, in some experiments, WiTricity specialists increased the transmission power to three kilowatts (and, remember, they started with a 60-watt light bulb). The efficiency varies depending on a whole set of parameters, however, according to the corporation, with sufficiently close coils it can exceed 95%.

It is not difficult to guess that a promising method of transmitting electricity over several meters without wires and the need to aim some kind of “power beams” should be of interest to a wide range of companies. Some are already working in this direction on their own.

For example, starting from the principles substantiated and tested by Soljachich and his colleagues, Intel is now developing its modification of resonant power transmission - Wireless Resonant Energy Link (WREL). Back in 2008, the company achieved brilliant results in this field, demonstrating “magnetic” current transmission with an efficiency of 75%.

One of the experienced Intel installations WREL, which wirelessly transfers power (along with an audio signal) from an MP3 player to a small speaker (photo from gizmodo.com).

Sony is now conducting its own experiments, reproducing the experiments of physicists from the Massachusetts Institute of Technology.

However, Soljačić is confident that his innovation will not be lost among the products of his fellow competitors. After all, it was the pioneers of the technology who made the most of it and are ready for its in-depth study and improvement. For example, setting up even a pair of coils is not as simple as it seems at a superficial glance. The scientist carried out experiments in the laboratory for several years in a row before he built a system that works truly reliably.

Demo sample of LCD screen receiving electrical power through the first prototype of the WiTricity household kit. The transmitting coil lies on the floor, the receiving coil is on the table (photo WiTricity).

"Wireless Electricity", according to its authors, was originally intended to be an OEM product. Therefore, in the future we can expect the appearance of this technology in the products of other companies.

And a trial balloon towards potential consumers has already been launched. In January in Las Vegas at CES 2010 Chinese company Haier showed the world's first complete wireless HDTV TV. Not only the video signal from the player was transmitted to its screen over the air (for which the Wireless Home Digital Interface standard, which was officially born just a month earlier, was used), but also the power supply. The latter was provided precisely by WiTricity technology.

Soljachich’s company is also negotiating with furniture manufacturers about installing coils in tables and cabinet walls. The first announcement of a serial product from a WiTricity partner is expected by the end of 2010.

In general, experts predict the emergence of real bestsellers on the market - new products with a built-in WiTricity receiver. Moreover, no one can yet say with confidence what kind of things they will be.

Haier is one of the world's largest manufacturers of consumer electronics. It is not surprising that its engineers became interested in the possibility of combining the latest technologies for wireless transmission of an HDTV signal and wireless power supply, and even managed to be the first to show such a device in action (photos engadget.com, gizmodo.com).

Interestingly, the story of WiTricity began several years ago with a series of unfortunate awakenings for Marin. Several times over the course of a month, he was awakened by the sound of a dead phone asking him to “eat.” A scientist who forgot to connect his mobile phone to the socket in time was surprised: isn’t it funny that the phone is located a few meters from electrical network, but is unable to receive this energy. After waking up again at three in the morning, Soljachich thought: it would be great if the phone could take care of its charging itself.

Note that we are not immediately talking about a new version of “mats” for charging pocket devices. Such systems only work if the device is placed directly on the “mat”, and for forgetful people this is no better than having to simply plug the wire into an outlet. No, the phone had to receive electricity anywhere in the room, or even the apartment, and it didn’t matter whether you threw it on the table, sofa or windowsill.

Here, ordinary electromagnetic induction, directed microwave rays and “cautious” infrared lasers were not suitable. Marin began looking for other options. He could hardly have thought then that after some time a beeping and “hungry” telephone would lead him to the creation of his own company and the emergence of a technology capable of “making headlines” and, more importantly, of interest to industrial partners.

Let’s add that the corporation’s executive director, Eric Giler, once spoke in some detail about the principles, history and future of WiTricity.