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When it comes to charging in life, your first reaction is whether to use a charger and a charging cable. In recent years, a number of "wireless chargers" have been on the market, which can be charged "in the air". What principles and technologies are used in this?
As early as 1899, physicist Nikola Tesla began his exploration of wireless power transmission. He built a wireless power transmission tower in New York, and conceived a method of wireless power transmission: using the earth as the inner conductor and the earth's ionosphere as the outer conductor, by amplifying the transmitter in the radial electromagnetic wave oscillation mode, established between the earth and the ionosphere It resonates at a low frequency of about 8Hz, and then uses the surface electromagnetic waves that surround the earth to transmit energy.
Although this idea was not realized at the time, it was a bold exploration of wireless charging by scientists a hundred years ago. Nowadays, people have continuously researched and tested on this basis, and successfully developed wireless charging technology. The original scientific concept is gradually being implemented.
Wireless charging is a technology that uses a non-physical contact method to achieve power transmission. At present, there are three common wireless power transmission technologies, namely electromagnetic induction, electromagnetic resonance, and radio waves. Among them, the electromagnetic induction type is a widely used method, which not only has high charging efficiency, but also has low cost.
The working principle of electromagnetic induction wireless charging technology is: install the transmitting coil on the wireless charging base, and install the receiving coil on the back of the mobile phone. When the mobile phone is charged close to the charging base, the transmitting coil will generate an alternating magnetic field because it is connected to the alternating current. The change in the magnetic field will cause an induced current in the receiving coil, which transfers energy from the transmitter to the receiver, and finally completes the charging process.
The charging efficiency of the electromagnetic induction wireless charging method is as high as 80%. In order to solve this problem, scientists have started a new attempt. In 2007, a research group in the United States successfully used electromagnetic resonance technology to light a 60-watt light bulb about 2 meters away from the power source, and the power transmission efficiency reached 40%, which started the research and development boom of electromagnetic resonance wireless charging technology. The principle of electromagnetic resonance wireless charging technology is the same as the resonance principle of sound: an energy transmitting device and an energy receiving device are adjusted to the same frequency, and the energy of each other can be exchanged during resonance, so that the coil in one device can be far away. The distance transfers power to a coil in another device, completing the charge. The electromagnetic resonance wireless charging technology breaks the limitation of electromagnetic induction short-distance transmission, extends the charging distance to 3 to 4 meters at the maximum, and also gets rid of the limitation that the receiving device must use metal materials when charging.
In order to further increase the distance of wireless power transmission, researchers have developed radio wave charging technology. The principle is: a microwave transmitting device and a microwave receiving device complete wireless power transmission, the transmitting device can be installed in a wall plug, and the receiving device can be installed on any low-voltage product. After the microwave transmitting device transmits the radio frequency signal, the receiving device can capture the radio wave energy bounced from the wall, and obtain stable direct current after wave detection and high-frequency rectification, which can be used by the load.
Compared with traditional charging methods, wireless charging technology breaks the limitations of time and space to a certain extent, and brings a lot of convenience to our lives. It is believed that with the further development of wireless charging technology and related products, there will be a broader future. application prospects.