There are three ways of wireless power supply: electromagnetic induction, magnetic induction resonance and microwave radiation.
Based on electromagnetic induction technology, the wireless charging / wireless power supply equipment we use now is produced according to the principle of electromagnetic induction. At least the commercial equipment we have now are electromagnetic induction principle equipment. At present, there are three ways to realize wireless power supply: electromagnetic induction mode, magnetic induction resonance mode and microwave radiation mode.
Most of the various wireless charging technologies seen today use electromagnetic induction technology. This technology can be regarded as a separate transformer, removing the middle conductive magnet (iron core). The coil at the transmitting end and the coil at the receiving end are placed in two separate devices. When electric energy is input to the coil at the transmitting end, a magnetic field will be generated. When the magnetic field induces the coil at the receiving end, it will generate current. In this way, a set of radio energy transmission system is constructed.
Because the middle guide magnet is removed, the magnetic field decreases rapidly with the increase of distance, and the distance of electric energy transmission is very short. Generally, it can only have a better transmission effect within a few millimeters, so it can only be applied to small wireless charging devices with small power. A key technical parameter of electromagnetic induction is that the hole spacing ratio is too small. If you want to transmit energy on the spacing between the door and the door frame, you need a very large coil, even much larger than the area of the mobile phone, which can not be tolerated by the door itself.
At present, the transmission power of microwave radiation is too small, and the principle is similar to WiFi signal transmission (in fact, the transmission of WiFi signal and other wireless signals can also be considered as an energy transmission mode, just because the energy is distributed in all directions, and the utilization rate is extremely weak). The transmission efficiency of microwave radiation is also far lower than that of electromagnetic induction and magnetic induction resonance, and there are certain radiation safety problems, so it is difficult to promote it in our intelligent lock industry.
Compared with electromagnetic induction, magnetic induction resonance emphasizes the concept of resonance. Through the reasonable calculation of coil and capacitance, the transmitting and receiving devices have the same resonant frequency. When the system works at this frequency, the transmitting and receiving coils resonate to complete the transmission of electric energy. Magnetic induction resonance is much farther away. Magnetic induction resonance uses two coils with exactly matched specifications. One coil generates a magnetic field after being energized, and the other coil can light the bulb or transmit power to the equipment.