The working principle of wireless charging

无线充的工作原理说到无线充电技术就必须先说一说特斯拉线圈，相信学过高中物理的人对尼古拉·特斯拉于1891年发明的特斯拉线圈都不会感到陌生，这是如今所有无线充电技术的原型。口语化来说，原理很简单，就是我们初中物理课学习的“磁共振技术原理”说的再简单点就是电生磁，磁生电！通过线圈产生磁场再经接收线圈，将磁场转化成电。

The Tesla coil is mainly composed of two coils. One of the coils is connected to a power supply whose current direction changes periodically with time. Under the action of this current, the first coil will generate a constantly changing magnetic field in space. When the second coil is induced in this magnetic field, it will generate current, which will light up the light bulb on the second coil, and replacing this light bulb with a battery becomes wireless charging. The principle can be roughly understood as follows: The strings vibrate, and the vibration wave will be transmitted to the surrounding objects, causing the surrounding objects to vibrate.

Academic point In detail, the wireless charging system mainly adopts the principle of electromagnetic induction, and realizes the energy transfer through the energy coupling of the coil. As shown in the figure, when the system is working, the input terminal converts the AC mains power into DC power through the full-bridge rectifier circuit, or the 24V DC terminal directly supplies power to the system.

The direct current output after passing through the power management module is converted into high-frequency alternating current and supplied to the primary winding through a 2M active crystal oscillator inverter. The energy is coupled through the two inductance coils, and the current output by the secondary coil is transformed into a direct current by the receiving conversion circuit to charge the battery.

A changing magnetic field will produce a changing electric field, and a changing electric field will produce a changing magnetic field. The magnitude of the change is related to their rate of change. The rate of change of the sine function is another sine function, so electromagnetic waves can propagate, and the induced voltage The generation of is related to the change of magnetic flux, so the changing magnetic field inside the coil generates an induced voltage to complete the charging process.

The simple summary is that the principle of mobile phone wireless charging is to separate the primary and secondary secondary of the ordinary transformer to achieve the purpose of wireless.