Solving the problem of wireless transmission of electrical energy over long distances is a long-standing dream of mankind. You can imagine how much cheaper electricity would be without the cost of current-carrying products. The scientific and technical revolution does not stand still. It is hoped that this dream will come true in the near future. This is evidenced by new developments in this area.
Despite this, scientists around the world are busy getting new technologies, the task of which is to transfer energy at a distance of tens or hundreds of kilometers. New scientific achievements in the field of electricity delivery without wire transmission lines are already being developed and implemented.
The great French physicist Ampere in 1820, through numerous experiments, came to the conclusion that a magnetic field can excite an electric current in a metal body. This is how the fundamental ampere law appeared. Michael Faraday in 1831 discovered the law of induction, which became the basis for the development of such a science as electromagnetism. James Maxwell, after much experimentation, systematized his observations, the quintessence of which in 1864 was the Maxwell equation. The formula explained the behavior of the electromagnetic field. Nikola Tesla improved the device for generating an electromagnetic field, invented by Heinrich Hertz in 1888. At the world's fair in 1893, held in Chicago, Tesla demonstrated the glow of phosphor bulbs without wires.
Russian scientist Alexander Popov made his contribution to the development of wireless energy transmission. In 1895, at a meeting of the Russian physical and chemical society, he showed a detector radio receiver that he had invented. Further, up to the present day, new inventions in the field of wireless transmission of electric energy were patented. A lot of experiments were made, and quite a lot of discoveries were made. The latest development in this field is the transmission of electricity over long distances without wires using Wi-Fi technology. In 2017, a mobile phone without a battery was invented.
How it works
Wireless electricity is based on such a phenomenon as electromagnetism. The work involves two coils of metal wires. One of them is connected to a current source, around which a magnetic field is created. The second coil, sensing this field, induces a secondary electric current in its winding.
Principles of transmission
The latest developments of scientists from the United States and South Korea used magnetic resonance systems CMRS and DCRS. The Korean technology was more advanced. We managed to transmit electricity for 5 meters. Thanks to the compact DCRs dipole coils, it is possible to power all consumers in a medium-sized room without wires.
Important! Imperfection of modern equipment significantly limits the length of the path of electricity through the air.
The most promising directions in the development of new methods and methods for transporting electricity without material contact are:
- ultrasonic method;
- electromagnetic induction method;
- electrostatic induction;
- microwave radiation;
- laser method;
- electrical conductivity of the Earth.
Ultrasonic method.
Students of the University of Pennsylvania (USA) at a recent exhibition in 2011 demonstrated a method for transmitting electric current using ultrasound. The transmitter generated acoustic waves in the ultrasonic range, and the receiver converted them into electric current. Ultrasound was not chosen as an energy carrier by chance. Its effect on the human body is absolutely harmless. The imperfection of this method is that the transmission efficiency is very low, you need direct visibility between subscribers and a limited distance (7-10 meters).
Method of electromagnetic induction.
The operation of an ordinary transformer gives an idea of how electricity is transmitted without wires by electromagnetic induction. Two coils are involved in the process. The magnetic field excited by the current flowing through the coils of the primary winding induces an electric flow in the secondary winding of the transformer. Examples of using the effect of electromagnetic induction can be smartphone chargers and electric toothbrushes. The disadvantage of this method of energy transfer is the unavoidable proximity of the coils. Even with a small increase in the gap between the windings, most of the energy begins to be dispersed in space. One type of electromagnetic induction is the use of resonance. The essence of the method is that the receiver and transmitter operate in the same frequency range. The transmitting and receiving devices are a solenoid with a single layer of turns. The generating device is equipped with a capacitor circuit, by which it is adjusted to the frequency of the receiver.
Electrostatic induction.
The method is based on the principle of energy passing through the body of a dielectric. This method is called capacitive coupling. The generator creates an electric field in the tank, which excites the potential difference between the two electrodes of the consumer. Nikola Tesla used the method of electrostatic induction to demonstrate a wireless lighting lamp. The lamp was powered by a high-frequency alternating electric field. It glowed steadily, regardless of its movement in the room.
Microwave radiation.
Space technology specialists have developed a method for transmitting electricity from orbiting solar panels to spacecraft using a microwave radio signal. The problem with this method is that receiving and transmitting beam radiation requires antennas with a very large aperture. NASA scientists in 1978 concluded that to transmit a microwave beam with a frequency of 2.45 GHz, the radiating antenna must have a diameter of 1 km reflecting surface. Each of rectenna should have a diameter of 10 km. It is possible to reduce these dimensions by using ultrashort waves. However, signals of this range are quickly absorbed by the atmosphere or blocked by rain.
Laser method.
The transmission of electricity over long distances without wires with the help of a laser began to carry out sosem recently. The idea is that a laser beam carrying an energy potential falls on a photocell of the receiving device, where high-frequency electromagnetic radiation is converted into an electric current. Laser energy transfer technology, previously used in the military field, is being successfully implemented in the civilian sphere of human activity. The development of American scientists led to the invention of an unmanned aerial vehicle that receives energy from a laser beam. In 2006, a drone was demonstrated that could fly in non-stop mode, powered by a laser installation. In 2009, an experiment was successfully carried out in space to transfer energy for one kilometer with a capacity of 500W.
Electrical conductivity of the Earth.
Đ¢here Is a theory of using the earth's subsurface and oceans for wireless energy transmission. The electrical conductivity of the hydrosphere, deposits of metal ores can be used to transmit low-frequency alternating current. Electrostatic induction of dielectric bodies can occur in huge deposits of quartz sand and similar minerals. Electric current can also be transmitted through the air by electrostatic induction. Nikola Tesla once suggested that in the future there will be technologies that will use the earth, ocean waters and the planet's atmosphere to transmit electricity.
Worldwide wireless system.
For the first time, the world's wireless power transmission system became known from the great scientist Tesla. In 1904, he stated that the creation of a VBS using the high electrical conductivity of plasma and Earth is quite feasible.
Real projects in our days.
Of all that the market of electrical engineering offers today, relate to the wireless transmission of electricity chargers for smartphones, electric toothbrushes. They use the principle of electromagnetic induction.
In the aircraft industry, serial production of flying drones powered by wireless transmission of electricity has begun. A small microwave helicopter with rectenna can rise to a height of up to 15 meters above the ground. There are drones that can fly in the field of view of the laser beam. Chinese manufacturer of home appliances Haier Group has been producing wireless LCD TVs since 2010.
Prospects for wireless transmission of electricity.
Currently, research is underway and projects are being developed to create electric vehicles that will move on the road surface with a current pipeline that induces an electric current in the vehicle's motor. A Number of leading companies are developing wireless power supplies that can supply electricity to all consumers within a single room. In the future, the appearance of routes consisting of a number of wireless sources of electricity, which will be able to move aircraft over long distances. With the advent of new materials, improved devices and inventions, wireless transmission of electricity in the near future will cover all areas of human activity.
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