We all know that wireless charging of mobile phones is very popular nowadays. What is its development history? What changes have been made to wireless charging of mobile phones? And what are the current wireless charging solutions for mobile phones? What are their advantages and disadvantages?

First, let's take a look at the history of wireless charging technology for mobile phones and see how it has evolved to the present.

Mobile wireless charging technology is not a "black technology". As early as the 19th century, modern scientists named Michael Farah discovered the principle of electromagnetic induction, that is, the change of the surrounding magnetic field will cause current in the wire. Today, the relatively mature wireless power transmission for smartphones has slowly spawned two wireless charging solutions:

The first is an electromagnetic induction wireless charging scheme.

This is the wireless charging technology solution with the highest frequency and the widest popularity in the industry. The principle is Faraday's battery induction law, which is to give the primary coil a certain frequency of alternating current, and generate a certain current in the secondary coil through electromagnetic induction. Energy is transferred from the transmission end to the receiving end.

Implemented on the mobile phone, it is embedded in the back cover of the mobile phone and in the wireless charging base, respectively embedded in the receiving end and the transmitting end dedicated coil (including conversion and identification, power management and other chips), when the power is input to the transmitting end coil A magnetic field is generated, and the magnetic field senses the coil at the receiving end to generate a current to achieve the charging process.

In theory, the larger the number of coils in the transmitting end and the receiving end, the larger the area, the more power is transmitted wirelessly per unit time, and the requirements for the distance and position between the two are more relaxed.

Advantages: low cost, mature technology and relatively high conversion efficiency.

Disadvantages: The charging distance is too short, and it is necessary to align the contacts to ensure the effect.

The second is a magnetic field resonant wireless charging scheme.

The solution consists of an energy transmitting device and an energy receiving device. When the transmitting end and the receiving end reach the same frequency, magnetic field resonance can be generated to satisfy the energy exchange, and the principle is similar to the resonance.

Compared with electromagnetic induction, the magnetic field resonance scheme has an effective transmission distance (supporting several centimeters to several meters) and enables one-to-many charging.

The magnetic field resonance type belongs to the electromagnetic induction type "advanced version". In theory, it is only necessary to add a capacitor in the secondary coil (in the mobile phone) to form a resonant circuit to resonate with a fixed frequency alternating current on the charging base, thereby realizing multi-device, Wireless charging over long distances.

Advantages: long charging distance, support one-to-many

Disadvantages: Charging multiple devices at the same time will increase heat generation and lower conversion efficiency, and increase efficiency will generate more electromagnetic radiation, which is not good for safety.

From the above point of view, both options have their own advantages and disadvantages. This also proves that there is still a lot of room for development in our wireless charging technology. I believe that our wireless charging technology will develop further in the future and bring greater benefits to our lives. In the end, we can not only charge quickly, but also safely charge at a long distance, and even play the phone while charging.