Not long ago, the source Komiya released the product list for Apple’s autumn online conference, including iPhone 12, Apple Watch, and AirTag. Perhaps the most eye-catching thing is that Apple will The long-delayed AirPower wireless charging pillow has been launched. Domestically, the mobile phone wireless charging market in 2020 has also begun a new round of arms race. From the world's first commercial 40W wireless fast charger on OPPO Ace2 to the 50W wireless fast charger on Xiaomi Mi 10 Pro, is the spring of wireless mobile phone charging coming?
01 Pioneers who have fallen one after another
When it comes to wireless charging, the first thing that comes to everyone’s mind should be Samsung mobile phones. Indeed, Samsung was the first mobile phone brand to widely use wireless charging. Starting from the Samsung S6, almost every generation of Samsung's mid-to-high-end mobile phones are equipped with wireless charging. However, the S6 released in 2015 was not the first mobile phone to support wireless charging. There was a "magic phone" that used this feature more than ten years ago.
This mobile phone is the Palm Pre released by Palm in 2009. The card-style task background and full-screen gesture interaction that we are already familiar with are all leftover from its onboard system webOS; epoch-making hardware such as light-emitting dots, wireless charging, and front and rear data cables are all available, as well as The special magnetic Palm Touchstone wireless charger has a charging power of 5W. No wonder Lei Jun calls it magical. However, Palm was acquired by HP in the second year, and several products launched after that received mediocre response, and eventually they were gradually submerged in the trend of iOS and Android.
Another mobile phone that supports wireless charging is the Lumia 920 released by Nokia in 2012. Like the Palm Pre, the Lumia 920 is also equipped with a lot of pioneering technologies: the first mobile phone in the industry to add an optical anti-shake component to the camera, the second mobile phone to support Qi standard wireless charging (the first is Sharp SH-13C), Bringing wireless charging into the public eye... With the end of the Windows Phone ecosystem, Nokia's mobile phone business has also come to an end.
In addition to these two foreign brands, the first domestic mobile phone to support wireless charging is the Gionee M7 Plus released in 2017, which also supports 14W wireless fast charging. It is a pity that after Gionee released this mobile phone, it began to decline, gradually faded out of the mobile phone market, and eventually went bankrupt.
02 AirPower, which has been difficult to produce for many years
From technological exploration to trying fast charging, wireless charging has attracted the "dedication" of generations of pioneers. It often happens that the first mobile phone manufacturer to take advantage of wireless charging fails halfway. This is of course only a small probability event and has nothing to do with technology. However, this also implies that wireless charging is not a good road to take.
In the post-Jobs era, Apple is relatively conservative in following up on new technologies. The Apple Watch, released in 2015, was the first Apple device to support wireless charging. After wireless charging has been used on Apple Watch for three generations, it was not until the iPhone X/iPhone 8 in 2017 that it supported Qi 1.1 standard 7.5W wireless charging. Also in this year, Apple proposed the concept of AirPower charging pillow.
The biggest highlight of AirPower is that the charging device can be placed anywhere, allowing users to charge iPhone, Apple Watch, AirPods and other devices that support wireless charging at the same time. In order to realize "a variety of devices can be placed at will", Apple has unprecedentedly built in a stack of 22 overlapping induction coils in AirPower. However, the coils interfere with each other, causing the device to heat up.
The overheating problem also caused AirPower to delay sales in 2018 and 2019. It was not until the Apple conference this fall that we had the opportunity to meet it.
03 Domestic wireless charging where power is king
Whether it is Samsung, which is stable, or Apple, which focuses on experience, the wireless charging power of mobile phones has not exceeded 15W for many years, and Apple is even more Sticking to the subsistence line of 7.5W, high power means uncontrollable heating problems and higher patent pool fees. However, domestic mobile phone manufacturers do not think so. In 2017, the first domestic wireless charging mobile phone, Gionee M7 Plus, increased the power to 14W. From then on, the concept of faster, better has completely taken root in the hearts of domestic manufacturers.
Compared with the current top-notch 15W Qi standard wireless fast charging, domestic wireless fast charging can be said to be like eight immortals crossing the sea, each showing its magical powers. Almost every manufacturer can come up with its own private wireless charging protocol. Huawei’s Wireless SuperCharge, Xiaomi’s wireless fast charging, Meizu’s Super Wireless mCharge, OPPO’s AIRVOOC, and OnePlus’ Warp wireless flash charging. The lowest power ranges from 27W to the highest 50W of Xiaomi 10 Pro. Even VIVO, which has been waiting to see, showed off a 60W wireless charging at APEX 2020.
Domestic mobile phone wireless charging technology can make rapid progress on the road of stacking power, but it still benefits from the application of charge pump technology. At present, common fast charging solutions include high voltage and low current and low voltage and high current to increase charging power. Charge pump technology can achieve both high voltage and high current. The principle is to use capacitors as energy storage components to perform voltage conversion. Xiaomi 9 uses this wired fast charging technology to increase the wireless charging power to 20W, and the charge pump technology does not change the electromagnetic induction wireless charging principle, so it can also support the Qi wireless fast charging standard.
04 Consumes 47% more power than wired charging
Wireless charging uses the principle of electromagnetic wave induction for charging, which is similar to a transformer. There is a coil at each of the sending and receiving ends. The sending end coil is connected to a wired power supply to generate an electromagnetic signal. The receiving end coil induces the electromagnetic signal at the sending end to generate current. There are four main ways to realize wireless charging technology: electromagnetic induction, magnetic field vibration, radio wave, and electric field coupling. However, due to technical and cost limitations, all current mobile phone wireless charging technologies are based on electromagnetic induction.
When it comes to wireless charging, the problem of conversion efficiency cannot be avoided. Based on electromagnetic induction wireless charging, the theoretical charging efficiency reaches 80%. But this is only theoretical efficiency, and the actual situation must be discounted. According to online test data, under the condition of 220 AC V power, when 30W wireless VOOC flash charging is turned on, the output power of the charging terminal is as high as 42.62W, which is much lower than the conversion efficiency of 80. This brings about a power consumption problem.
According to the latest estimates from the OneZero and iFixit teams, the power of wireless charging is much lower than that of wired charging. After multiple comparisons of wireless and wired charging on Pixel 4, it was found that on average wireless charging uses 47% more power than wired charging. It takes an average of 14.26 Wh to fully charge a phone using the wired method; while a wireless charger requires an average of 21.01 Wh. This amount of power may seem insignificant, but if it is spread evenly over the future and multiple devices and terminals use wireless as the main charging method, the power consumption will be very considerable.
05 Wireless charging, only mobile phones are not enough
According to IHS data, it is expected that by 2020, the shipment volume of wireless charging receivers will exceed 1 billion pieces, and the number of transmitters will also increase in 2021. It will reach a scale of approximately 500 million pieces. The global wireless charging market is expected to grow from US$1.7 billion in 2015 to US$15 billion in 2024, with a compound annual growth rate of 27.
Of course, most of these 1 billion wireless charging receivers are not mobile phones. They are mainly small IoT devices represented by smart wearable devices, new energy vehicles and other electronic consumer products.
As far as mobile phones are concerned, the main application scenario of wireless charging has never been to charge from the lowest power to full, but to "keep the power sufficient at all times." Occasionally pick up your phone to make and answer calls while at work, and you don’t have to worry about the phone’s battery when you’re off work; just put your phone away before going to bed and you can fall asleep peacefully. To sum up, wireless charging for mobile phones has three advantages: first, it uses fragmented time to keep the device fully charged, second, it protects the "chrysanthemum", and third, it is not bound by wires and can be taken anywhere.
So no matter how high the wireless charging power of mobile phones is, it is actually a useless feature for most people. Moreover, wireless charging functions are generally only installed on flagship models, and can cover even fewer users.
06 Wireless reverse charging and NFC charging are promising in the future
Contrary to mobile phones, the demand for wireless charging of wearable devices is currently very strong, such as smart watches and TWS headphone charging boxes Basically, they come standard with wireless charging function. Most of these products have limited battery capacity and are not so sensitive to charging power. They can even be charged using NFC. Nowadays, Android phones basically support wireless reverse charging. Xiaomi Mi 10 Pro has a reverse charging power of 10W. It can easily charge TWS headphone boxes and other small IoT devices, and it can also give Apple wireless "fast charging". charge".
Instead of developing high-power private wireless charging standards, I think the launch of the NFC charging standard will be of greater significance to the entire wireless charging ecosystem. The NFC charging standard launched in May uses a 13.56 MHz basic frequency and supports four power transmission levels of 250, 500, 750 and 1000 milliwatts. The power of just 1W is insignificant, but it solves the problem of having it or not.
The NFC charging standard is very suitable for small IoT devices with small battery capacity. Wireless charging can be achieved without adding additional coils and peripheral circuits, reducing costs and making the device smaller; for For mobile phones, the NFC charging standard can also bring wireless charging functions down to the thousand-yuan level. The popularity of mobile phones currently equipped with NFC functions is of great significance, and it also makes wireless reverse charging easier. The combination of wireless reverse charging and NFC charging should speed up the popularity of wireless charging. Wireless life has a promising future.
By the way, have you used wireless charging on your mobile phone?