Detailed explanation of Xiaomi's air charging technology

A few days ago Xiaomi released their air charging technology

The scene in the demo film is very sci-fi

Now let’s talk about some of the bottlenecks of air-to-air charging technology, as well as future applications and directions.

There are some practical problems that Xiaomi will not tell you

Overall, this kind of true wireless charging is indeed the future direction

But I highly doubt whether this concept product can really be launched

Even if the product is mass-produced,

Because it involves millimeter wave modulation, transmission, and a series of high-cost components of phased array antennas.

I estimated it myself

Even if the product is launched, the price is at least a few thousand higher.

And there are many descriptions in the demo, which are very unrealistic

For example, Xiaomi claims that it is not afraid of foreign objects.

These propaganda points can almost be considered impossible

So I take this opportunity to have a good chat with everyone behind the technology

You don’t understand and there is a high probability that Xiaomi will never be able to confess these things to you.

Let’s talk about things. I’m not trying to black Xiaomi.

Domestic manufacturers are proud to be the first to launch and implement this technology

But this technology currently has many problems and limitations

I don’t think Xiaomi can solve it perfectly in a short time

The technical direction is right, but there is still a lot of room for improvement.

The scenes shown in Xiaomi's promotional video are very limited

There is no mention of shortcomings and some practical problems of air charging

So I want to clarify with you all aspects of the so-called air-to-air charging technology

So that everyone has a more comprehensive understanding so that they can have their own judgments

This is the purpose of this video

The wireless charging methods we use nowadays are actually all contact types.

For example, the well-known mobile phone wireless charging board

But the concept of wireless charging is actually quite misleading

We are used to calling it that way, it doesn’t mean that this should be the final form of wireless charging.

The charging method of the wireless charging pad should actually be called "electromagnetic induction wireless charging"

The principle is to use alternating current to convert the electromagnetic field of the transmitter coil dozens of times per second. The magnetic field conversion will drive the receiver coil to cause "resonance"

So that the electromagnetic energy is converted into alternating current and then converted into direct current to charge the battery

You can understand resonance like this

You imagine that two goblets are put together very close and you knock on one of them

Then cover it with your hands and don’t let it make any more noise. Listen carefully to the other goblet

You will find that the other goblet is also driven by the sounding goblet next to it to make a sound.

This is the energy transfer caused by resonance

Electromagnetic induction uses a similar principle

However, the distance between the two sets of coils is strictly limited

If you want to be efficient, you have to be close

Humans’ initial vision for wireless charging was to transmit electricity over long distances.

Through electromagnetic induction

Physically speaking, it is impossible to achieve true long-distance power transmission.

The induced magnetic field attenuates exponentially as the physical distance increases

The efficiency of wireless charging achieved by electromagnetic induction coils will also be greatly reduced according to the extension of the physical distance.

There are probably only two ways to achieve long-distance power transmission.

One is through electromagnetic waves, which is Xiaomi’s so-called air charging technology

The use of millimeter-wave microwaves is actually microwave power transmission. This technology is very mature.

The radiating component array is used as a phased array antenna to achieve beamforming and beam steering

Receiving array rectenna that transmits narrowband electromagnetic waves to the terminal of the mobile phone in a directional direction

Then convert the collected energy into direct current and then charge it into the battery

Learn more about the basics used in Xiaomi's air charging technology

One is the phased array antenna and the other is beamforming

Just now I said that long-distance power transmission is in addition to electromagnetic waves

There is also a technology that can achieve long-distance energy transmission

Is the way of light energy

Whether it’s laser beam or infrared

All have related experimental techniques and some niche commercial products

The military actually has technology that uses light energy as a carrier to transfer energy.

For example, the "Deuteron Laser Power Transmission System" of "Impluse Gundam"

You can use the mothership Minerva to launch deuteron laser beams to deliver these electrical energy to the "Mobile Suits"

So I hope everyone understands that Xiaomi’s air charging technology is actually not a new thing.

The technology of electromagnetic induction to transmit electricity through the air has been studied by Intel in the early years.

The prototype machine has long been able to provide wireless power with 60 watts of power within a range of a few meters.

However, Intel’s main business has been declining in recent years.

Everyone knows this, so some time ago they cut off the follow-up research and development of wireless charging technology.

There are even many organizations internationally formulating related technical standards, such as "AirFuel"

There are many related applications for long-distance wireless power transmission in the form of electromagnetic waves.

The GSM mobile phones in the early years were more powerful

GSM electromagnetic waves can even drive the pendant small LED lights on the phone to flash when the call comes.

I don’t know how many people born in the 80s remember this gadget

Later, the 3G 4G base station has increased the communication efficiency by dozens or hundreds of times.

But the communication power has been reduced a lot

On the contrary, you can't bring this kind of small pendant to get electricity from the air.

The uniqueness of Xiaomi's air charging technology is that they use electromagnetic waves in the millimeter wave frequency band.

Through the phased array antenna of the indoor power supply base station, beamforming and beam steering can be realized

It can track the position of the mobile phone's receiving rectenna in real time

And then focus on launching a very narrow electromagnetic beam to the mobile phone

In fact, beamforming and steering use the phased array antenna N many radiation components to interfere with each other to change the phase of electromagnetic waves.

Simply put, it is a lot of radiating components

For example, the radiating component here emits electromagnetic waves normally

The radiation component on the side is delayed a little bit, and the next side is delayed a bit

Then the main lobe of this electromagnetic wave is roughly heading in this direction.

I explained the principle of beamforming in detail in the last video.

If you want to know more deeply, don’t forget to click here to take a look

Many friends know that I am good at cloud analysis.

Because the product is the surface layer and the technology is the bottom layer

The application of technology to the market is a slow process

The underlying technology of these products we use actually appeared in the laboratory very early.

Moreover, the entire industry driven by this technology and the new applications in the future are more worthy of attention.

Let me give you an example. Let’s say you put a charging base station in the shape of a ceiling light on top of your house.

Your mouse, keyboard, watch, home camera, game console, and various sensors may not require batteries.

It’s like plugging in a power cord that you can’t see all the time

Of course, this is the ideal state. We are still facing the problem of attrition.

When will there be an explosive breakthrough in human power generation capacity?

For example, the global power generation has increased by 10 times or even 100 times in an instant.

Then we can ignore the loss of these wireless transmission problems

Currently this is just a good vision

Is this technology currently only capable of 5 watts of power supply? Will it have more power to supply power in the future?

If millimeter waves are used to transmit electric energy, it can only be applied to small devices in the short term.

For example, the mouse, keyboard, headset, sensor, etc. I just mentioned.

I didn’t talk about TV’s air-conditioning and stereo, right

Because the electromagnetic wave with too high frequency attenuates too much

I think 5 watts is a hurdle at present, even if it can reach 10 watts or even higher in the future

For some large electrical appliances, it still can’t carry

The air conditioner may have kilowatts, right? This power

Therefore, millimeter wave power transmission will continue to be a method for small power equipment in the general direction.

Large-scale electrical equipment is still the priority to consider shortening the transmission distance

It may be more reasonable to use low-frequency electromagnetic waves or electromagnetic induction coils

Or simply plug in the power cord

And wireless power transmission may be related to many factors

For example, the area material of the rectenna

Large equipment can do this kind of large rectenna

Better collection of low-frequency electromagnetic waves, relatively divergent electromagnetic beams emitted to achieve higher efficiency

In short, I still think that the charging equipment corresponding to the millimeter wave should be miniaturized or even millimeter-level electronic products.