Physicists have long known that energy can be effectively transmitted between two objects having the same resonance frequency, and the interaction between objects having different frequencies is weak. The singer's singing can shatter one of the different water bottles without affecting the other. It is also like when we are swinging, just sitting on the top and letting the legs swing in synchrony can give the swing the same power. Wireless charging technology takes advantage of this principle. Similarly, wireless charging technology also applies the principle of electromagnetic wave induction, and the related AC induction technology. A technology that sends and receives the generated AC signal at the sending and receiving ends to send and receive the induced AC signal, the user only needs to Charging devices can be charged on a "flat", which used to appear on watches and razors, but was unable to effectively charge large-capacity lithium-ion batteries.
A new type of wireless charger was originally invented by a British company. It looks like a plastic mouse pad. This “mouse pad” has dense arrays of small coils, so it can generate magnetic fields and transfer energy to a dedicated device. Receiving the electronic device of the coil to charge it. The receiving coil is made of a magnetic alloy wound around a wire and its size and shape are similar to those of chewing gum, so it can be easily attached to electronic equipment. Placing a cell phone or the like on the pad will charge it, and it will charge multiple devices at the same time. Charging technology has appeared before, but this new invention is more convenient and practical. Mobile phones and other devices can be charged at any position on the "mouse pad" as long as they are attached to the receiving coils. Unlike previous technologies, they do not require precise positioning. Several devices are placed on the mat at the same time and can be charged at the same time. The magnetic field generated by the charger is very weak and can charge the device without affecting nearby credit cards, videotapes, and other items that use magnetic recording data.
The wireless charging system mainly adopts the principle of electromagnetic induction, energy coupling through the coil to achieve energy transfer. As shown in the figure, when the system is working, the input terminal will convert the AC mains power into DC power through a full-bridge rectifier circuit, or use a 24V DC power supply directly to supply power to the system.
After passing through the power management module, the DC output is converted into high-frequency alternating current through the 2M active crystal oscillator to supply the primary winding. By coupling the energy of the two inductive coils, the current output by the secondary coil is changed into a direct current by the receiving converter circuit to charge the battery.
The changing magnetic field will produce a changing electric field. The changing electric field will produce a changing magnetic field. Its size is related to their rate of change, and the rate of change of the sine function is another sine function, so the electromagnetic wave can propagate out and the induced voltage The generation of the magnetic flux is related to the change of the magnetic flux, so the magnetic field inside the coil generates an induced voltage, thereby completing the charging process.
Mobile phone wireless charging is a relatively novel charging method. Its principle is actually very simple. It is to separate the ordinary transformer main and secondary to achieve the purpose of wireless. Of course, the operating frequency of wireless charging is relatively high, and it is even possible to abandon the core directly to achieve energy transfer between the coils.