Principle of magnetic coupling resonance in wireless power transmission
This method requires two resonance systems, transmitting and receiving, which can be made of induction coils respectively.
By adjusting the transmitting frequency to make the transmitting end vibrate at a certain frequency, it produces a non radiative magnetic field instead of an ordinary electromagnetic wave, that is, it converts electric energy into a magnetic field and forms an energy channel between two coils. The natural frequency of the receiver is the same as that of the transmitter, so resonance occurs. With each resonance, more voltage will be generated in the receiver inductor. After many times of resonance, the surface of the sensor will gather enough energy, so that the receiving end can receive energy in this non radiative magnetic field, so as to complete the conversion of magnetic energy to electric energy, and realize the wireless transmission of electric energy. The unreceived energy is reabsorbed by the transmitter.
This kind of non radiative electromagnetic field has a limited range and is not suitable for long distance. It requires that the distance between the transmitter and the receiver is within 8 times of the radius of the induction coil.