Russian scientists have developed a highly efficient wireless power transmission system. It can be used to create rooms where mobile phones and tablets will be charged automatically, "from the air."
At the beginning of the 20th century, Nikola Tesla first tested the possibilities of wireless transmission of electricity, but until recently the technology was practically not used or improved.
In 2007, a team of scientists at the Massachusetts Institute of Technology (MIT) tested WPT technology again: they turned on a 60-watt light bulb from a distance of two meters. The power transmission efficiency was 45 percent.
Later, the technique was repeatedly tried to rethink and improve, in particular, to increase the efficiency of energy delivery "through the air".
Based on the same principles, a team of Russian researchers led by Polina Kapitanova from St. Petersburg National Research University of Information Technologies, Mechanics and Optics and Elizaveta Nenasheva from Girikond Research Institute have created an improved wireless power transmission system based on resonant communication. The effectiveness of this method, according to numerical simulations, is 80 percent at a distance of 20 centimeters, and decreases slightly with increasing distance.
Let us explain the general principle of operation of such a system. The first copper coil transfers energy to the second coil, which operates with it at the same resonant frequency, just as an opera singer can transmit enough energy with his voice to break a glass (the resonant frequency of the voice coincides with the frequency that destroys the vessel).
Usually, magnetic fields are used to transfer energy, since they weakly interact with most surrounding objects, including the human body.
Russian researchers have slightly modified the originally developed system. So, instead of ordinary magnetic coils, special dielectric resonators are used in the form of ceramic spheres with a high dielectric constant. Such ceramic spheres can reduce transmission energy losses and thus increase efficiency.
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In addition, the material from which the spheres are made has a high refractive index, which means that electromagnetic waves in the spheres are greatly slowed down. This feature helps to enhance magnetic resonance and, as a result, further increase the efficiency of energy transfer.
Another innovation to reduce losses and increase efficiency: the transition to a higher order resonant frequency. “We suggest using the magnetic quadrupole method rather than the magnetic dipole method,” Kapitonova said in an interview with phys.org. They differ in the shape and strength of the generated magnetic field.
It is noted that in this case the transmitter and receiver do not need to be precisely aligned with each other for better energy transfer.
We add that other objects that will be in the "recharging room" have completely different resonant frequencies, due to which they will not be able to receive the transmitted energy. Accordingly, such a universal charging will be safe for the surrounding objects.
In the future, for practical use, Russian scientists plan to reduce the size of the resonators. “We are currently working on the creation and experimental study of a sample of the next version of the WPT system. We have developed new ceramic resonators with a higher dielectric constant. We believe that this prototype will be very close to practical use,”adds Kapitonova.
An article in the scientific journal Applied Physics Letters tells about the research in detail.
Note that scientists have long been trying to improve the process of charging a mobile phone, without which no modern person can do. So, Chinese developers have created a device that charges a smartphone with light.