How does wireless charging works?

All phones will support wireless charging in future?
About Qi standards

In recent years, many domestic flagship phone is with the function of wireless charging, speaking of wireless charging people must think of wireless charging is like WIFI, as long as our mobile phones within a certain scope can like mobile phone reception to cell phone charging, so we are now many phones also support the wireless charging, but when it’s charging the phone on a pad, so let’s look at our mobile phone wireless charging on what principle?

Since it is wireless charging, why should the phone be charged in the designated area of the charging pad?Our current wireless charging ways mainly has four kinds of electromagnetic induction, magnetic resonance, to electric field coupling, and a kind of is the way of waves, that in the four ways for now inside the electromagnetic induction technology is more mature, this way the charging efficiency is higher and its circuit structure is simple, so we currently use the cell phone is this kind of electromagnetic induction type.

The working principle of electromagnetic induction type is also very simple, people will go to school in physics class has been on the pad and phone has two coils respectively, when the pad coil, after turning on the power supply to the following with alternating current coil will generate a changing magnetic field, when we put the phone on the charging pad on the mobile phone back cover will be induced by the coil in the change of magnetic field coil on the mobile phone back cover and inductive current, and then give us the current into direct current mobile phone battery recharged, thereby realizing the wireless charging.

However, at present, its effective charging distance is within 10mm, and we need to put it in the center when charging. If it is not in the center, it will directly affect the efficiency of wireless charging.