Now wireless charging technology has been used in many aspects of our lives, and even now we are studying wireless charging cars. Do you know how wireless charging works?
I. interaction between electricity and magnetism
Common wireless charging adopts the principle of "current magnetic effect" and "electromagnetic induction".
In 1819, Danish scientists first discovered that if an electric current was applied to a wire, it would generate a magnetic field around it, which would deflect the compass needle.
Later, it was found that the magnetic field generated by winding the wire into a loop would be stronger and more concentrated, which is called the current magnetic effect.
As for electromagnetic induction, Faraday discovered it in 1831.
When a magnet or other magnetic field source is placed near a coil without current, the "induced current" on the coil is called "electromagnetic induction".
It is important to note that electromagnetic induction works only when the magnetic field "changes", for example as the magnet gets closer (farther and farther).
If the external magnetic field remains constant, there will be no induced current.
In short, the current magnetic effect is that the current produces a magnetic field around it, and the electromagnetic induction is an ever-changing external magnetic field, which causes the coil to produce an induced current.
II. Electromagnetic induction charging
The combination of these two physical phenomena can realize wireless charging.
The current wireless charging equipment includes "charging socket", which is actually the coil.
After connecting the charging socket to the household plug, due to the magnetic effect of the current, a magnetic field will be generated around the coil.
There are also coils inside the electronics to be charged. When it is close to the charging base, the magnetic field of the charging base will be induced by electromagnetic induction to generate current on the coil of the electronic product, and then charge the electronic product.
The inductive current guides the battery to complete the wireless charging between the charging socket and the electronic products.
You may ask that the magnetic field must be changed in order to generate electromagnetic induction. The distance between the charging base and the charging object remains the same. Why does electromagnetic induction occur?
It turns out that the current flowing out of the household socket is "alternating current", which means that the direction of the current is changing continuously. Therefore, the magnetic field generated by the charging baseline circle changes direction continuously according to the electromagnetic induction conditions, rather than keeping constant.
At present, wireless charging technology is still restricted by quite a lot, and we need to overcome many difficulties.