[PConline Truth-Seeking Lab] Wireless charging is a thing, supporters love it, but other people question its slow charging speed, short charging distance, and essentially take off your pants and fart. Whether you love it or not, you can't deny that wireless charging is really going to be popular.

For wireless charging, our expectation is, of course, to be free from constraints and to charge anytime, anywhere in a free space. Of course, the ideal is very full, and the reality is very skinny. With the current technology, wireless charging does not have many advantages compared with wired charging. In addition to the convenience of charging at any time without plugging in, the charging speed still cannot be compared with wired fast charging. Comparable, it cannot meet the needs of some users for using mobile phones while charging.

However, for some users, the current wireless charging can already be played. In some scenarios where the mobile phone is not frequently used, wireless charging can give full play to its advantages.

The technical principle of wireless charging

The core principle of wireless charging is based on electromagnetic induction, and the principle is not complicated. At present, there are two main technology branches in the industry, one is the magnetic field induction technology represented by the Qi standard, and the other is the magnetic resonance technology represented by the AirFuel standard.

In principle, magnetic resonance is a better solution, it supports a longer charging distance, and can support multiple devices charging at the same time. However, the magnetic resonance technology is not mature at present, and through the stacking of multiple coils, the Qi standard wireless charger can also charge multiple devices at the same time.

However, magnetic resonance is still the future development direction of wireless charging, and Qi also incorporates magnetic resonance technology into its standards. It can be seen that short-range power transmission is not impossible.

Wireless charging devices on the market

At present, the wireless charging standard used by smartphones and consumer wireless chargers on the market is mainly Qi, so as long as the mobile phone supports Qi wireless charging, theoretically all wireless chargers using the Qi standard are compatible (including those that are particularly difficult to serve). iPhone).

However, the charging efficiency of different mobile phones and wireless chargers is actually different. For wireless chargers, only the input and output power are generally listed, but for mobile phones, the received power is the key indicator to determine the charging efficiency. Generally, Say, the received power is about 75% of the output power.

charging pad

At present, the mainstream wireless chargers mainly use the Basic Power Profile configuration of Qi, which supports 10W output, which is equivalent to the received power of 5W~7.5W, including the conversion rate.

However, this year, wireless chargers using the Extended Power Profile configuration standard have been born one after another, which can support a maximum output power of 15W, which is equivalent to a receiving power of about 10W, which can greatly improve the wireless charging speed of mobile phones.

  Mobile terminal

Since wireless charging pads have power limitations, the same goes for mobile phones. The current mainstream smartphones (most of which use the Basic Power Profile configuration) support wireless chargers with an output power of 5 to 10W.

For example, Samsung Galaxy S series mobile phones can support 10W wireless charging, while Apple iPhone 8/8 Plus and iPhone X can support 7.5W wireless charging, of course, the received power will be lower.

In addition, smartphones that support the relatively fast wireless standard Extended Power Profile have also been launched this year. At present, there are the familiar Sony XZ2 series and LG V30 series. The receiving power can reach about 10W, but it needs to be equipped with the same configuration that supports Extended Power Profile. wireless charger.

To sum up, different mobile phones need to be equipped with different specifications of wireless chargers, but for most mobile phones, a wireless charger that supports 10W output is enough. In addition, many wireless chargers do not necessarily come with charging heads and data cables, and need to be selected according to their input power and fast charging standards.

Although the iPhone 8/8 Plus and iPhone X are compatible with the Qi standard, not all Qi wireless chargers can achieve 7.5W fast charging. For details, please refer to the following article: "Must Look for Mfi! Talk to you about the tricks of Apple's wireless charging"

Besides power, what else is there to focus on?

FOD foreign body detection

FOD foreign object detection should be the most basic safety function of wireless chargers. When a metal foreign object is sandwiched between the mobile phone and the wireless charger, the wireless charger will sense and power off to prevent the metal foreign object from overheating.

However, the FOD function cannot be judged just by looking at the propaganda parameters. You can only see the specific performance through actual measurement. Most of the wireless chargers on the market are qualified in terms of FOD foreign body detection.

  cooling problem

The output power of the wireless charger is not constant, and the peak power mainly depends on the design materials and heat dissipation methods of the wireless charger. We recommend buying a model equipped with an active cooling fan. Although it is thicker, the output peak power is generally higher. time also.

charging distance

The maximum charging distance of the Qi wireless charger is about 10 mm, so it can also be charged with a protective case, and it is not necessary to "strip" the phone to charge.

With the development and iteration of the Qi standard, the cost of wireless charging technology has gradually come down. There are more and more products around 100 yuan, and the experience cost is considered low. At present, Xiaomi and Huawei have begun to try to add wireless charging to their products. It can be expected that the wireless charging function will be more popular this year and next.