We do wireless transmission of electricity. Introduction to Wireless Power Transmission DIY Wireless Power

In fact, in the 1970s, he technically realized the dreams of NATO and the United States of constant air patrols of Iraq (Libya, Syria, etc.) with drones with cameras, hunting (or fixing) "terrorists" on-line 24 hours.

In 1968, the American space research specialist Peter E. Glaser proposed placing large solar panels in geostationary orbit, and transmitting the energy they generate (5-10 GW level) to the Earth's surface with a well-focused beam of microwave radiation , then convert it into energy of direct or alternating current of technical frequency and distribute it to consumers.

Such a scheme made it possible to use the intense flux of solar radiation that exists in the geostationary orbit (~ 1.4 kW/sq.m.) and transmit the received energy to the Earth's surface continuously, regardless of the time of day and weather conditions. Due to the natural inclination of the equatorial plane to the plane of the ecliptic with an angle of 23.5 degrees, a satellite located in a geostationary orbit is illuminated by a flux of solar radiation almost continuously, except for short periods of time near the days of the spring and autumn equinoxes, when this satellite falls into the Earth's shadow. These periods of time can be accurately predicted, and in total they do not exceed 1% of the total length of the year.

The frequency of electromagnetic oscillations of the microwave beam must correspond to those ranges that are allocated for use in industry, scientific research and medicine. If this frequency is chosen to be 2.45 GHz, then meteorological conditions, including thick clouds and heavy precipitation, have little effect on the efficiency of power transmission. The 5.8 GHz band is tempting because it allows you to reduce the size of the transmitting and receiving antennas. However, the influence of meteorological conditions here already requires further study.

The current level of development of microwave electronics allows us to speak of a rather high efficiency of energy transfer by a microwave beam from a geostationary orbit to the Earth's surface - about 70% ÷ 75%. In this case, the diameter of the transmitting antenna is usually chosen to be 1 km, and the ground-based rectenna has dimensions of 10 km x 13 km for a latitude of 35 degrees. SCES with an output power level of 5 GW has a radiated power density in the center of the transmitting antenna of 23 kW/m², in the center of the receiving antenna - 230 W/m².

Various types of solid-state and vacuum microwave generators for the SCES transmitting antenna were investigated. William Brown showed, in particular, that magnetrons, which are well mastered by the industry, designed for microwave ovens, can also be used in transmitting antenna arrays of SCES, if each of them is provided with its own negative feedback circuit in phase with respect to an external synchronizing signal (so called Magnetron Directional Amplifier - MDA).

The most active and systematic research in the field of SCES was conducted by Japan. In 1981, under the guidance of professors M. Nagatomo (Makoto Nagatomo) and S. Sasaki (Susumu Sasaki), research was started at the Space Research Institute of Japan to develop a prototype SCES with a power level of 10 MW, which could be created using existing launch vehicles. The creation of such a prototype allows one to accumulate technological experience and prepare the basis for the formation of commercial systems.

The project was named SKES2000 (SPS2000) and received recognition in many countries of the world.

In 2008, Marin Soljačić, assistant professor of physics at the Massachusetts Institute of Technology (MIT), was awakened from a sweet sleep by the persistent beeping of a mobile phone. “The phone would not stop, demanding that I put it on charge,” Soljacic said. Tired and not going to get up, he began to dream that the phone, once at home, would start charging by itself.

In 2012-2015 University of Washington engineers have developed technology that allows Wi-Fi to be used as an energy source to power portable devices and charge gadgets. The technology has already been recognized by Popular Science magazine as one of the best innovations of 2015. The ubiquity of wireless data transmission technology itself has made a real revolution. And now it's the turn of wireless power transmission over the air, which the developers from the University of Washington called (from Power Over WiFi).

During the testing phase, the researchers were able to successfully charge low-capacity lithium-ion and nickel-metal hydride batteries. Using the Asus RT-AC68U router and several sensors located at a distance of 8.5 meters from it. These sensors just convert the energy of an electromagnetic wave into a direct current with a voltage of 1.8 to 2.4 volts, which is necessary to power microcontrollers and sensor systems. The peculiarity of the technology is that the quality of the working signal does not deteriorate. It is enough just to reflash the router, and you can use it as usual, plus supply power to low-power devices. One demonstration successfully powered a small, low-resolution covert surveillance camera located more than 5 meters away from a router. Then the Jawbone Up24 fitness tracker was charged to 41%, it took 2.5 hours.

To tricky questions about why these processes do not negatively affect the quality of the network communication channel, the developers replied that this becomes possible due to the fact that a flashed router sends out energy packets during its work on unoccupied information transfer channels. They came to this decision when they discovered that during periods of silence, energy simply flows out of the system, and in fact it can be directed to power low-power devices.

During the study, the PoWiFi system was placed in six houses, and the residents were invited to use the Internet as usual. Load web pages, watch streaming video, and then tell them what's changed. As a result, it turned out that network performance did not change in any way. That is, the Internet worked as usual, and the presence of the added option was not noticeable. And these were only the first tests, when a relatively small amount of energy was collected over Wi-Fi.

In the future, PoWiFi technology may well serve to power sensors built into household appliances and military equipment in order to control them wirelessly and carry out remote charging / recharging.

Relevant is the transfer of energy for UAVs (most likely, already by technology or from a carrier aircraft):

The idea looks quite tempting. Instead of today's 20-30 minutes of flight time:
→
→

→ Intel ran the drone show during Lady Gaga's US Super Bowl halftime performance-
get 40-80 minutes by wirelessly charging drones.

Let me explain:
-exchange of m / y drones is still necessary (swarm algorithm);
- the exchange of m / y drones and aircraft (womb) is also necessary (control center, correction of knowledge base, retargeting, command to eliminate, preventing "friendly fire", transfer of intelligence information and commands to use).

Who's next in line?

Note: A typical WiMAX base station radiates at approximately +43 dBm (20 W), while a mobile station typically transmits at +23 dBm (200 mW).

Permissible levels of radiation from mobile base stations (900 and 1800 MHz, the total level from all sources) in the sanitary-residential zone in some countries differ markedly:
Ukraine: 2.5 µW/cm². (the most stringent sanitary standard in Europe)
Russia, Hungary: 10 µW/cm².
Moscow: 2.0 µW/cm². (the norm existed until the end of 2009)
USA, Scandinavian countries: 100 µW/cm².

The temporary allowable level (TDU) from mobile radiotelephones (MRT) for users of radiotelephones in the Russian Federation is defined as 10 μW / cm² (Section IV - Hygienic requirements for mobile land radio stations SanPiN 2.1.8 / 2.2.4.1190-03).

In the USA, the Certificate is issued by the Federal Communications Commission (FCC) for cellular devices whose maximum SAR level does not exceed 1.6 W/kg (moreover, the absorbed radiation power is reduced to 1 gram of human tissue).

In Europe, according to the international directive of the Commission on Non-Ionizing Radiation Protection (ICNIRP), the SAR value of a mobile phone should not exceed 2 W / kg (with the absorbed radiation power given to 10 grams of human tissue).

More recently, in the UK, a level of 10 W/kg was considered a safe SAR level. A similar pattern was observed in other countries as well. The maximum SAR value accepted in the standard (1.6 W/kg) cannot even be safely attributed to “hard” or “soft” standards. The standards for determining the SAR value adopted both in the USA and in Europe (all the regulation of microwave radiation from cell phones in question is based only on the thermal effect, that is, associated with the heating of human tissues).

COMPLETE CHAOS.

Medicine has not yet given a clear answer to the question: is mobile / WiFi harmful and how much? And what about the wireless transmission of electricity by microwave technology?

Here the power is not watts and miles of watts, but already kW ...

Links, used documents, photos and videos:
"(JOURNAL OF RADIOELECTRONICS!" N 12, 2007 (ELECTRIC POWER FROM SPACE - SOLAR SPACE POWER PLANTS, V. A. Banke)
"Microwave electronics - prospects in space energy" V. Banke, Ph.D.
www.nasa.gov
www. whdi.org
www.defense.gov
www.witricity.com
www.ru.pinterest.com
www. raytheon.com
www. ausairpower.net
www. wikipedia.org
www.slideshare.net
www.homes.cs.washington.edu
www.dailywireless.org
www.digimedia.ru
www. powercoup.by
www.researchgate.net
www. proelectro.info
www.youtube.com

When it appeared, alternating electric current seemed fantastic. Its inventor, the brilliant physicist Nikola Tesla, studied the problem of wireless transmission of electricity over long distances at the turn of the 19th and 20th centuries. So far, this problem has not been completely solved, but the results obtained are encouraging.

Ultrasound for energy transfer

Any wave carries energy, including high frequency sound waves. There are three approaches to wireless transmission of electricity:

transmission of electrical energy through conversion to another type of energy in the source and reverse conversion into electricity in the receiving device;
creation and use of alternative conductors of electricity (plasma channels, columns of ionized air, etc.);
use of the conductive properties of the Earth's lithosphere.

The method of applying ultrasound belongs to the first approach. In a special type of ultrasound source, when power is applied, a directed beam of high-frequency sound waves is generated. When they hit the receiver, the energy of the sound waves is converted into an electric current.

The maximum transmission distance of electricity without wires is 10 meters. The result was obtained in 2011 by representatives of the University of Pennsylvania during a presentation at the exhibition "The All Things Digital". This method is not considered promising due to several of its shortcomings: low efficiency, low resulting voltage and limitation on the strength of ultrasound radiation by sanitary standards.

Application of electromagnetic induction

Although most people are not even aware of it, this method has been used for a very long time, almost from the very beginning of the use of alternating current. The most common AC transformer is the simplest wireless power transmission device, only the transmission distance is very short.

The primary and secondary windings of the transformer are not connected in one circuit, and when an alternating current flows in the primary winding, an electric current arises in the secondary. The transfer of energy in this case occurs through an electromagnetic field. Therefore, this method of wireless transmission of electricity uses the conversion of energy from one form to another.

A number of devices based on this method have already been developed and are successfully used in everyday life. These are wireless chargers for mobile phones and other gadgets, and household electrical appliances with low power consumption during operation (compact video surveillance cameras, all kinds of sensors, and even LCD TVs).

Many experts argue that electric vehicles of the future will use wireless technologies for charging batteries or generating electricity for movement. Inductive coils (analogues of the primary winding of a transformer) will be mounted in the roads. They will create an alternating electromagnetic field, which, when a vehicle passes over it, will cause an electric current to flow in the built-in receiving coil. The first experiments have already been carried out and the results obtained cause restrained optimism.

Among the advantages of this method can be noted:

high efficiency for short distances (of the order of several meters);
simplicity of design and mastered application technology;
relative safety for human health.

The disadvantage of the method - a small distance at which the energy transfer is effective - significantly reduces the scope of wireless electricity based on electromagnetic induction.

Using different microwaves

This method is also based on the conversion of different types of energy. Electromagnetic waves of ultrahigh frequency serve as a carrier of energy. This method was first described and practically implemented in his installation by the Japanese physicist and radio engineer Hidetsugu Yagi in the twenties of the last century. The frequency of radio waves for the transmission of electricity without wires is in the range from 2.4 to 5.8 GHz. An experimental installation has already been tested and received positive feedback, which simultaneously distributes Wi-Fi and powers low-power household electrical appliances.

A laser beam is also electromagnetic radiation, but with a special property - coherence. It reduces energy losses during transmission and thereby increases efficiency. Of the advantages, the following can be noted:

the possibility of transmission over long distances (tens of kilometers in the Earth's atmosphere);
convenience and ease of installation for low-power devices;
the presence of visual control of the transmission process - the laser beam is visible to the naked eye.

The laser method also has disadvantages, namely: a relatively low efficiency (45–50%), energy losses due to atmospheric phenomena (rain, fog, dust clouds) and the need to find the transmitter and receiver in the field of view.

The intensity of sunlight outside the earth's atmosphere is several tens of times higher than on the surface of the earth. Therefore, in the future, according to futurologists, solar power plants will be located in near-Earth orbit. And the transfer of accumulated electricity, in their opinion, will be carried out without current-carrying wires. A transmission method that copies lightning discharges will be developed and applied, it is planned to produce air ionization in one way or another. And the first experiments in this direction have already been carried out. This method is based on the creation of alternative wireless conductors of electric current.

The wireless electricity obtained in this way from near-Earth orbit is impulsive. Therefore, for its practical application, powerful and inexpensive capacitors are needed, and it will also be necessary to develop a method for their gradual discharge.

Most efficient method

Planet Earth is a huge capacitor. The lithosphere mainly conducts electricity, except for small areas of it. There is a theory that wireless transmission of energy can be carried out through the earth's crust. The gist is this: the current source is in reliable contact with the earth's surface, an alternating current of a certain frequency flows from the source into the crust and spreads in all directions, electric current receivers are placed in the ground at certain intervals, from which it is transmitted to consumers.

The essence of the theory is to accept and use the current of only one given frequency. Just as the frequency of receiving radio waves is tuned in a radio receiver, so in such electrical receivers the frequency of the received current will be adjusted. Theoretically, by this method it will be possible to transmit electricity over very long distances if the frequency of the alternating current is low, of the order of a few Hz.

Prospects for wireless transmission of electricity

In the near future, a massive introduction of a PoWiFi system into everyday life is expected, consisting of routers with the function of transmitting electricity over several tens of meters, and household appliances, which are powered by receiving electricity from radio waves. Such a system is currently being actively tested and is being prepared for widespread use. Details were not disclosed, but according to the available information, the “zest” is that synchronization of the electromagnetic fields of the source and receiver of wireless electricity is used.

In the very distant future, the option of abandoning the use of traditional power plants on a global scale is being considered - solar stations will be used in low Earth orbit that convert sunlight energy into electrical energy. Electricity will presumably be transmitted to the surface of the planet through ionized air or plasma channels. And on the earth's surface itself, conventional power lines will disappear, their place will be taken by more compact and efficient systems for transmitting electricity through the lithosphere.

For many years, scientists have been struggling with the issue of minimizing electrical costs. There are different ways and proposals, but the most famous theory is the wireless transmission of electricity. We propose to consider how it is carried out, who is its inventor and why it has not yet been brought to life.

Theory

Wireless electricity is literally the transmission of electrical energy without wires. People often compare the wireless transmission of electrical energy to the transmission of information such as radios, cell phones, or Wi-Fi Internet access. The main difference is that radio or microwave transmission is a technology aimed at restoring and transporting exactly information, and not the energy that was originally spent on transmission.

Wireless electricity is a relatively new area of technology, but one that is growing rapidly. Methods are now being developed to efficiently and safely transfer energy over a distance without interruption.

How does wireless electricity work

The main work is based precisely on magnetism and electromagnetism, as is the case with radio broadcasting. Wireless charging, also known as inductive charging, is based on a few simple principles of operation, in particular, the technology requires two coils. A transmitter and receiver that together generate an alternating, non-constant current magnetic field. In turn, this field causes a voltage in the receiver coil; this can be used to power a mobile device or charge a battery.

If you direct an electric current through a wire, then a circular magnetic field is created around the cable. Despite the fact that the magnetic field affects both the loop and the coil, it manifests itself most strongly on the cable. When you take a second coil of wire that does not have an electric current passing through it, and place the coil in the magnetic field of the first coil, the electrical current from the first coil will be transmitted through the magnetic field and through the second coil, creating an inductive coupling.

Let's take an electric toothbrush as an example. In it, the charger is connected to an outlet that sends an electric current to a coiled wire inside the charger, which creates a magnetic field. There is a second coil inside the toothbrush, when the current starts to flow and, thanks to the formed magnetic field, the brush starts charging without it being directly connected to the 220 V power supply.

Story

Wireless power transmission as an alternative to the transmission and distribution of electric lines was first proposed and demonstrated by Nikola Tesla. In 1899, Tesla presented a wireless transmission to power a field of fluorescent lamps located twenty-five miles from a power source without the use of wires. But at the time, it was cheaper to wire 25 miles of copper wire rather than build the custom electrical generators that Tesla's experience requires. He was never granted a patent, and the invention remained in the bins of science.

While Tesla was the first person to demonstrate the practical possibilities of wireless communication back in 1899, today, there are very few devices on sale, these are wireless brushes, headphones, phone chargers and more.

Wireless technology

Wireless power transmission involves the transmission of electrical energy or power over a distance without wires. Thus, the core technology lies on the concepts of electricity, magnetism and electromagnetism.

Magnetism

It is a fundamental force of nature that causes certain types of material to attract or repel each other. Earth's poles are considered the only permanent magnets. The current flow in the loop generates magnetic fields that differ from oscillating magnetic fields in the speed and time required to generate alternating current (AC). The forces that appear in this case are shown in the diagram below.

This is how magnetism appears

Electromagnetism is the interdependence of alternating electric and magnetic fields.

Magnetic induction

If a conducting loop is connected to an AC power source, it will generate an oscillating magnetic field in and around the loop. If the second conducting loop is close enough, it will pick up some of this oscillating magnetic field, which in turn generates or induces an electric current in the second coil.

Video: how is the wireless transmission of electricity

Thus, there is an electrical transfer of power from one cycle or coil to another, which is known as magnetic induction. Examples of such a phenomenon are used in electrical transformers and generators. This concept is based on Faraday's laws of electromagnetic induction. There, he states that when there is a change in the magnetic flux connected to the coil, the EMF induced in the coil is equal to the product of the number of turns of the coil and the rate of change of the flux.

power clutch

This part is necessary when one device cannot transmit power to another device.

A magnetic link is generated when an object's magnetic field is capable of inducing an electrical current with other devices within its reach.

Two devices are said to be mutually inductively coupled or magnetically coupled when they are designed such that a change in current occurs when one wire induces a voltage at the ends of the other wire through electromagnetic induction. This is due to the mutual inductance

Technology

The principle of inductive coupling

The two devices, mutually inductively coupled or magnetically coupled, are designed such that the change in current as one wire induces a voltage at the ends of the other wire is produced by electromagnetic induction. This is due to mutual inductance.
Inductive coupling is preferred due to its ability to operate wirelessly as well as shock resistance.

Resonant inductive coupling is a combination of inductive coupling and resonance. Using the concept of resonance, you can make two objects work depending on each other's signals.

As you can see from the diagram above, resonance provides the inductance of the coil. The capacitor is connected in parallel to the winding. Energy will move back and forth between the magnetic field surrounding the coil and the electric field around the capacitor. Here, radiation losses will be minimal.

There is also the concept of wireless ionized communication.

It is also feasible, but here you need to make a little more effort. This technique already exists in nature, but there is hardly any reason to implement it, since it needs a high magnetic field, from 2.11 M/m. It was developed by the brilliant scientist Richard Volras, the developer of the vortex generator, which sends and transmits heat energy over great distances, in particular with the help of special collectors. The simplest example of such a connection is lightning.

Advantages and disadvantages

Of course, this invention has its advantages over wired methods, and disadvantages. We invite you to consider them.

The advantages include:

Complete absence of wires;
No power supplies needed;
The need for a battery is eliminated;
Energy is transferred more efficiently;
Significantly less maintenance required.

The disadvantages include the following:

Distance is limited;
magnetic fields are not so safe for humans;
wireless transmission of electricity, using microwaves or other theories, is practically impossible at home and with your own hands;
high installation cost.

Discovered by André Marie Ampère in 1820, the law of interaction of electric currents laid the foundation for the further development of the science of electricity and magnetism. After 11 years, Michael Faraday experimentally found that a changing magnetic field generated by an electric current is capable of inducing an electric current in another conductor. That's how it was created.

In 1864, James Clerk Maxwell finally systematized Faraday's experimental data, giving them the form of exact mathematical equations, thanks to which the basis of classical electrodynamics was created, because these equations described the relationship of the electromagnetic field with electric currents and charges, and the existence of electromagnetic waves should have been a consequence of this.

In 1888, Heinrich Hertz experimentally confirmed the existence of electromagnetic waves predicted by Maxwell. His Rumkorff coil interrupted spark transmitter could produce electromagnetic waves up to 0.5 gigahertz, which could be received by multiple receivers tuned to resonance with the transmitter.

The receivers could be located at a distance of up to 3 meters, and when a spark appeared in the transmitter, sparks also appeared in the receivers. So were held first experiments in wireless transmission of electrical energy using electromagnetic waves.

In 1891, while studying alternating currents of high voltage and high frequency, he came to the conclusion that it is extremely important for specific purposes to select both the wavelength and the operating voltage of the transmitter, and it is not at all necessary to make the frequency too high.

The scientist notes that the lower limit of frequencies and voltages at which he managed to achieve the best results at that time is from 15,000 to 20,000 oscillations per second at a potential of 20,000 volts. Tesla received a high frequency and high voltage current by applying an oscillatory discharge of a capacitor (see -). He observed that this kind of electrical transmitter was suitable both for the production of light and for the transmission of electricity for the production of light.

In the period from 1891 to 1894, the scientist repeatedly demonstrates wireless transmission and the glow of vacuum tubes in a high-frequency electrostatic field, while noting that the energy of the electrostatic field is absorbed by the lamp, transforming into light, and the energy of the electromagnetic field used for electromagnetic induction in order to obtain a similar The result is mainly reflected, and only a small fraction of it is converted into light.

Even using resonance when transmitting using an electromagnetic wave, a significant amount of electrical energy cannot be transmitted, the scientist argued. His goal during this period of work was to transmit precisely a large amount of electrical energy in a wireless way.

Until 1897, in parallel with the work of Tesla, research on electromagnetic waves was carried out by Jagdish Bose in India, Alexander Popov in Russia, and Guglielmo Marconi in Italy.

Following Tesla's public lectures, Jagdish Bose speaks in November 1894 in Calcutta with a demonstration of wireless transmission of electricity, where he ignites gunpowder, transmitting electrical energy over a distance.

After Boche, namely April 25, 1895, Alexander Popov, using Morse code, transmitted the first radio message, and this date (May 7, according to the new style) is now celebrated annually in Russia as "Radio Day".

In 1896, Marconi, having arrived in the UK, demonstrated his apparatus, transmitting a signal using Morse code over a distance of 1.5 kilometers from the roof of the post office building in London to another building. After that, he improved his invention and managed to transmit a signal along the Salisbury Plain already at a distance of 3 kilometers.

Tesla in 1896 successfully transmits and receives signals at a distance between transmitter and receiver of about 48 kilometers. However, none of the researchers has managed to transmit a significant amount of electrical energy over a long distance.

Experimenting in Colorado Springs, in 1899 Tesla wrote: "The inconsistency of the method of induction seems to be enormous in comparison with the method of excitation of the charge of the earth and air." This will be the beginning of the scientist's research aimed at transmitting electricity over long distances without the use of wires. In January 1900, Tesla would record in his diary the successful transfer of energy to a coil "far out in the field" from which the lamp was powered.

And the most grandiose success of the scientist will be the launch on June 15, 1903 of the Wardenclyffe tower on Long Island, designed to transmit electrical energy over a considerable distance in large quantities without wires. The grounded secondary winding of the resonant transformer, crowned with a copper spherical dome, had to excite the charge of the earth and the conductive layers of air in order to become an element of a large resonant circuit.

So the scientist managed to power 200 lamps of 50 watts at a distance of about 40 kilometers from the transmitter. However, based on economic feasibility, funding for the project was stopped by Morgan, who from the very beginning invested in the project in order to get wireless communications, and the transfer of free energy on an industrial scale over a distance did not suit him as a businessman. In 1917, the tower, designed for the wireless transmission of electrical energy, was destroyed.

Much later, in the period from 1961 to 1964, an expert in the field of microwave electronics, William Brown, experimented in the USA with microwave energy transmission paths.

In 1964, for the first time, he tested a device (a model of a helicopter) capable of receiving and using the energy of a microwave beam in the form of direct current, thanks to an antenna array consisting of half-wave dipoles, each of which is loaded with high-performance Schottky diodes. Already by 1976, William Brown had transmitted a power of 30 kW by a microwave beam over a distance of 1.6 km with an efficiency exceeding 80%.

In 2007, a research group at the Massachusetts Institute of Technology, led by Professor Marin Solyachich, managed to wirelessly transmit energy over a distance of 2 meters. The transmitted power was enough to power a 60 watt light bulb.

Their technology (called ) is based on the phenomenon of electromagnetic resonance. The transmitter and receiver are two copper coils resonating with the same frequency, each 60 cm in diameter. The transmitter is connected to a power source, and the receiver is connected to an incandescent lamp. The circuits are tuned to a frequency of 10 MHz. The receiver in this case receives only 40-45% of the transmitted electricity.

Around the same time, a similar technology for wireless power transmission was demonstrated by Intel.

In 2010, Haier Group, a Chinese home appliance manufacturer, unveiled its unique product, a fully wireless LCD TV based on this technology, at CES 2010.