Recently Xiaomi released 200W wired charging and 120W wireless charging technology，Let the mobile phone charge time be within 8 minutes。Zhitiao, as a few industry media, was invited to have in-depth exchanges with Xiaomi fast charging engineers.。
Engineers related to Xiaomi's fast charging technology analyzed the charging technology released by Xiaomi this time in a deeper way，Including charging devices、Battery Materials、Adjustment of charging algorithm and architecture、optimization，And he also made his own judgment on the future development of fast charging technology。
one、Can high-power charging and lightweight really not be used at the same time?
fast charge、High power、Flirtatiousness always seems to be a contradictory existence，And the trade-offs between them，You can also see what kind of user experience a manufacturer focuses on。Lei Jun and Xiaomi engineers agree that charging、battery life、The three aspects of lightness and thinness are all three very important dimensions of mobile phones。
Lei Jun once mentioned，The charging speed and the energy density of the battery cannot be used at the same time.，In order to achieve a relatively balance between speed and lightness, Xiaomi，The energy density of the 10C battery is achieved to the extreme，Minimize the impact of "reduced energy density caused by fast charging" as much as possible。
Xiaomi engineer said，Although the word "light" is simple，But the requirements for engineers are very high，Such high-power fast charging technology stacks onto a thin and light phone，Need to get a battery、cooling、All stacked，This presents a more stringent challenge to all engineers and experts，Xiaomi has a dedicated team to do the ultimate stacking design。
Talking about lightness，Just talk about battery life，This demonstration machine has a thickness of about 9mm and a 4000mAh battery，Obviously there is still a lot of room for improvement。
Xiaomi engineer said，Xiaomi has its own battery life and DOU model，A lot of effort has been made to optimize the battery life of each machine。
Except for the thinness of the phone，The portability of the charger is also important。Xiaomi engineer said，Through the new gallium nitride technology，The switching frequency is twice as high as 120W，Many energy storage devices can be used with smaller ones。
In addition, Xiaomi has replaced traditional winding transformers with planar transformers，200The volume of W transformer is smaller than that of 120W，It can basically achieve the same size as 120W，It is said that it may be smaller after mass production。
two、Fast charging may not damage the battery，What do you think of Xiaomi’s 50W wireless charging restrictions?
How to maintain battery life under higher frequency fast charging，It is an issue that manufacturers need to pay great attention to。
Xiaomi adopts a 10C graphene-based design this time，Give the battery high electron conduction and ion conduction characteristics，Xiaomi has selected positive and negative battery materials with high stability for the 10C system，A specially designed electrolyte solution for 10C，Achieve better protection of battery materials。
allegedly，The battery used by Xiaomi 200W fast charging can meet 800 cycles and maintain energy of more than 80%，The national standard is to maintain 60% energy after 400 cycles。
The safety of charging has always been a concern for ordinary consumers。Xiaomi engineer said，This time Xiaomi's 200W fast charging is from the charging temperature、Charging voltage、The charging current and charging protocol are protected.，There are more than 40 safety protection measures in total。
For example, in terms of motherboard design，Xiaomi uses independent MCU with charging algorithm，When a communication exception occurs、When the software crashes, etc., the charging status is abnormal，The MCU can quickly cut off the high-power fast charging path。
Xiaomi adds some corrosion-resistant rhodium-ruthenium alloy materials to the Type-C port，Can reduce the corrosion of fast charging on Type-C interface，In addition, Xiaomi has designed an over-temperature protection detection circuit on the Type-C port，When the charging port temperature is detected to be too high, the charging power can be reduced in time or the charging circuit diameter can be cut off.。
Also, the battery itself，Xiaomi customized and developed a 10C high-power fast charging architecture，Negative graphite with fast ion ring，Provides a fast channel for lithium ion embedded in negative graphite，Can protect the battery from safe fast charging。
Safety，I have to say that there is fever，This time Xiaomi 200W fast charging adopts a parallel design，Power conversion efficiency is 98.6%，It is said to be the highest in the industry。Multi-stage transition current algorithm is used in software。
In 120W wireless charging technology，Xiaomi uses the latest multi-strand winding technology on its coil，Optimized nanocrystal shielding material，Ensure high power efficiency will not be lost。
In terms of cooling system，Xiaomi placed a VC heat-efficient board directly at the charging IC，The heat on the front of the battery is dissipated through the aluminum alloy middle frame，The heat on the back is dispersed through specially thickened graphite flakes that account for more than 60% of the mobile phone.。It is said that under these technologies and designs，200The charging temperature is basically the same as 120W。
Currently，The rapid development of wireless charging technology has also attracted the attention of the Ministry of Industry and Information Technology，The Ministry of Industry and Information Technology issued a draft for soliciting opinions some time ago，Wireless charging power limit is not more than 50W，This aspect is also considered in terms of charging safety。
to this，Xiaomi engineer said，The action of the Ministry of Industry and Information Technology shows that the country has begun to regulate wireless charging，This is a good thing。After the state starts to control，Third-party accessories products on the market will improve the quality of their own products，Better control of radiation。
certainly，50W limit in soliciting opinions，Xiaomi still feels a little low，Currently, we are also actively communicating with the Ministry of Industry and Information Technology。But Xiaomi engineers said clearly，This will ultimately depend on the opinions of the Ministry of Industry and Information Technology，If the country's policies are implemented，Xiaomi will definitely follow the national regulations。
In Xiaomi's view，They prefer not to set power limits，Instead, it achieves safety by limiting radiation。
three、When will air charging come? Charging compatibility is still the biggest problem
Not long ago, Xiaomi also launched the air-to-air charging technology，Xiaomi engineer said，Xiaomi cooperates with scientific research institutions，It has been developed for a long time，The complexity and difficulty of this technology are not as good as the current magnetic induction wireless charging energy。
But currently certified、Regulations and safety are very important issues，Xiaomi has done a lot of preliminary research and research in the above aspects，There are also technical reserves，Lay the foundation for the future to continue to develop the next generation of charging technology。
Nowadays, users still have great pain points in the compatibility of mobile phone charging，Different brands of mobile phones have their own private charging protocols，Charger charging other brands of mobile phones can only be charged at very low power。In fact, achieving the unity of rules and standards in the future should be the general direction of mobile phone charging development。
Xiaomi engineer said，Actually, we are developing our own private agreement，To ensure the safety of high-power charging。certainly，This also creates some compatibility issues。
However, after the efforts of the Telecom Terminal Industry Association，National group standards integration fast charging agreement is actively moving forward，This will increase the charging power compatible with chargers of different brands。
Currently Xiaomi、Huawei、OPPO、Vivo and other manufacturers are actually developing towards "one charger charges all devices"，A charger solves not just a mobile phone，And laptop computer、Fast charging for tablets and other devices。Therefore, every company has to solve the compatibility problem.。
Four、Charging to form a "command team"，Two years of "recharge" to the first place
Wired and wireless charging have always been one of Xiaomi's core technologies，It is also the self-developed technology that Lei Jun emphasized at the Xiaomi Developer Conference。
Currently, Xiaomi and charging-related expert team、Technical engineers are mainly distributed in Beijing、Shanghai、Shenzhen、Four R&D centers in Nanjing，Areas involved、Many departments and teams，Including baseband teams related to motherboard charging architecture design，Battery、data line、Team of connectors and chargers，Structural cooling team，Software development team，There are also test teams and so on。
According to Xiaomi engineers，2017 Mid-year and end of the year，Xiaomi's charging expert team has begun to be established，The goal was set at that time，"Can you do the fastest charging technology in the industry?" Lei Jun and a number of executives attach great importance to the research and development of charging technology.。
2019 Early every year，After more than a year of hard work，Xiaomi releases 100W wired fast charging，In August last year, 120W wired charging technology was launched first。In the field of fast charging，Xiaomi has indeed been ahead of the industry in the past two years。
five、200After W，Where is the limit of fast charging，When will wireless replace wired?
The development of mobile phone fast charging is beyond our imagination，2019 The charging power of mobile phones is still around 65W，And in 2020, it has reached more than 100,000 yuan，2021 It has reached 200W in the year，It is growing at an average annual rate。
So is there any upper limit on fast charging power development? Regarding this，Xiaomi engineer said，5 PD released a fast charging protocol upgrade in the month，Although it is a draft，But it has supported 240W technology。
Future technological evolution is inseparable from the exploration of new technologies and material upgrades，Including charging chips、Battery and charger、data line、Interfaces, etc.。If the battery charge power can be higher one day、Lower impedance、Be more efficient，Theoretically, charging technology will continue to be upgraded。
In terms of wireless charging，Xiaomi engineer mentioned，The main reason why wired charging still dominates，On the one hand, the ecological construction of wireless charging is not perfect，Few wireless charging devices in public places，And low power。
Although wireless charging technology is developing very rapidly，But it's not mature enough compared to wired charging，The charging experience is not as convenient as wired charging。
But in the future, when wireless charging technology and ecological construction are relatively complete，Even the mobile phone interface will be cancelled，Xiaomi engineer reveals，Perhaps some manufacturers' mobile phones may cancel the charging interface next year and the next year.。
epilogue："Hundred Watts Fast Charging" is far from the end of mobile phone charging
Through in-depth exchanges with Xiaomi engineers，I see behind Xiaomi 200W wired charging and 120W wireless charging，Xiaomi is customizing devices、Battery Materials、Charging algorithm、Innovations in stacking design，You can also feel Xiaomi's research and development of core technologies such as charging，It is taken seriously。
But we can see，No matter how thin and thin the wired charging faces、battery life、Technical challenges of choosing between speed，Or the construction of wireless charging ecosystem，There are still many problems waiting for the engineers to overcome。
No matter how charging technology develops，Convenient for our daily use、Upgrade our charging experience，It's the direction that always remains unchanged，We also look forward to the future Xiaomi、OPPO、Top players such as vivo can bring more innovative charging "black technology" 。
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Article Source：https://www.ithome.com