At present, the types of wireless charging technology are: electromagnetic induction mode, electromagnetic resonance mode, electric field coupling mode, and radio wave mode.
Among them, electromagnetic induction technology and electromagnetic resonance technology are the main technologies used in mobile phone wireless charging solutions. Of course, once wireless charger breaks through the technical barriers, it will also have a very broad prospect in the future household appliances, as well as in electric vehicles with a growing momentum.
Electromagnetic induction mode
As we know, the transformer widely used nowadays consists of a core and two coils (primary coil and secondary coil). When an alternating voltage is added to the two ends of the primary coil, an alternating magnetic field will be generated in the core, thus inducing an alternating voltage of the same frequency on the secondary coil, and the electric energy will be input from the electricity. The circuit is transmitted to the output circuit. If the coil at the transmitting end and the coil at the receiving end are placed in two separate devices, when the electric energy is input into the coil at the transmitting end, a magnetic field will be generated, and the magnetic field will be induced to the coil at the receiving end, and the current will be generated. Thus, we construct a radio power transmission system.
The main disadvantage of this system is that the magnetic field decreases rapidly with the increase of distance, and can only work in the range of several millimeters to 10 centimeters. In addition, the energy is divergent in all directions, so the induced current is far less than the input current, and the energy efficiency is not high. But for objects in close contact, there is no problem.
The earliest wireless charging product based on this principle is electric toothbrush. Because electric toothbrush often touches water, the use of cordless phone charging station can make charging contacts not exposed, enhance the waterproof of products. Also, it can be washed as a whole.
Electromagnetic induction is characterized by short transmission distance and relatively fixed position, but it has high energy efficiency and simple technology. It is very suitable for wireless charging technology.