1: Electromagnetic induction, a simple understanding is the principle of a transformer, which sends electrical energy to the primary coil, so that the secondary coil is coupled and induced to generate a current, thereby achieving "wireless" transmission of energy from one end to the other. The principle and hardware requirements of this method are relatively simple. It has achieved scale, its production cost is low, and it has been tested by the market and is more popular.
The disadvantage is that the transmission distance is too short due to the limitation of the technical principle. As the distance increases, the loss of wireless charging will increase and the efficiency will decrease. So this is why the phone cannot be charged when it is a little farther away from the wireless charging pad.
2: Electromagnetic resonance, a simple understanding is the "upgraded version" of electromagnetic induction. Essentially, it uses electromagnetic resonance technology to improve the transmission efficiency of electromagnetic induction in the case of loose coupling, so as to achieve longer while ensuring efficiency The transmission distance (charging distance and charging area are more than 10 times higher than the electromagnetic induction method), compared with the electromagnetic induction type, the characteristics of the electromagnetic resonance type are obviously more in line with the needs of wireless charging of electric vehicles
3: Because the radio wave type converts electromagnetic waves into electrical energy, the balance between power and safety is difficult, and it is rarely used at present.
There are still many shortcomings of wireless charging, there are too many immature technologies, and it is generally believed that the radiation problem needs time to verify. Real wireless charging still has a long way to go!