Wireless charging technology originated from wireless power transmission technology and can be divided into two ways: low-power wireless charging and high-power wireless charging. Low-power wireless charging often adopts electromagnetic induction, such as Qi method for mobile phone charging, but ZTE's electric vehicle wireless charging adopts induction method. High-power wireless charging often adopts resonance type (most electric vehicles charge in this way). The power supply equipment (charger) transmits energy to the electric equipment, and the electric equipment uses the received energy to charge the battery and provide it for its own operation. Because the charger and the electrical equipment transfer energy by magnetic field, there is no wire connection between them, so both the charger and the electrical equipment can be exposed without conductive contacts. Alternating current with a certain frequency in the primary coil generates a certain current in the secondary coil through electromagnetic induction, thus transferring energy from the transmitting end to the receiving end.
At present, the most common charging scheme is electromagnetic induction. In fact, there is not much mystery in the technical realization of electromagnetic induction solution. As early as 65438+February 2005, China BYD Company applied for the patent of non-contact induction charger, which adopted electromagnetic induction technology. It consists of an energy transmitter and an energy receiver. When two devices are tuned to the same frequency or vibrate at a specific frequency, they can exchange each other's energy. This is a technology being studied before a project. The research team led by MarinSoljacic, a physics professor at MIT, used this technology to light a 60-watt light bulb two meters away and named it WiTricity. The diameter of the coil used in this experiment reaches 1250px, so it cannot be commercialized. If the coil size is reduced, the received power will naturally decrease.