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The magnetic materials in the wireless charging

The magnetic materials in the wireless charging

Update Time:2020/7/2
Wireless charging has become popular in mobile phones, and they become standard devices. There are also a lot of products in the wearable space. In the future, wireless charging will be widely used in homes, offices, public places, transportation tools and transportation. There will also be widespread use of electric cars in the future.
Application of wireless energy transmission (WPT) : smart phone, smart wear (small power)
The structure of wireless charging
It is similar to that of a transformer, which consists of a transmitter and a receiver, both of which are composed of coils and magnetic materials. There are different kinds of magnetic materials, such as ferrite, amorphous and nanocrystalline.

The role of soft magnetic shielding material in wireless charging
Magnetic shielding: provides a low impedance path for magnetic flux, reduces the magnetic field lines emitted to the outside, reduces the impact on the surrounding metal objects, and prevents eddy current and signal interference.
Magnetic resistance reduction: improve coupling coefficient, improve magneto-electric conversion efficiency,  use fewer turns to achieve higher inductance coil, reduce coil resistance, reduce the efficiency reduction  caused by heat (more turns, higher resistance).
Comparison of charging efficiency of nanocrystalline magnetic conducting tablets
In order to simulate the real situation and conduct comparative test under the same conditions, the charging efficiency of nanocrystalline magnetizers with different thickness and ferrites with different permeability and thickness are compared. With the increase of the thickness, the charging efficiency is improving, but the nanocrystalline is not thicker, and it is basically saturated at 0.1mm. Therefore, when designing the wireless charging module, the nanocrystalline magnetic conducting plate does not need to be too thick, which will increase the material cost. The rule of ferrite is similar to that of nanocrystalline. The higher the permeability, the higher the charging efficiency, and the thicker the thickness, the higher the charging efficiency. However, at the same charging efficiency, the thickness of nanocrystalline magnetic sheet is only half of that of ferrite.

Application cases
Nanocrystalline applications for wireless charging began with S7, a material that does all the work, replacing a combination of amorphous and ferrite. It is generally believed that used in the NFC soft magnetic materials, ferrite is the best, and that nanocrystalline doesn't fit, because in high frequency, the wastage of the nanocrystalline outweigh the ferrite, but  research personnel made a breakthrough, the successful application of S7 proved nanocrystals can be used in the NFC, then the S8 / N8 / A7 / J5 / J7 many models such as products, to expand the application of nanocrystalline from WPC to NFC and MST.
 Mobile phone wireless charging development trend:
 1,Function: the WPC - WPC + NFC - WPC/Airfule + NFC
 2,Wireless charging -- wireless charging + -- charging at will
 3,Power: the 5 W - 7.5 W - > 10 W - 15 W
 4,Slow charge -- universal charge -- quick charge -- flash charge

Application and popularization

Low power: mobile phone, smart wear, etc

Medium power: computer, kitchen appliances, etc

High power: electric vehicles, roads and other infrastructure

The future, will be the wireless world, change life, change the world.