Wireless charging is simple in concept. The two coils form a special transformer, the primary is in the charger, and the secondary is in the charging device. However, if you have ever owned a wireless charging device, you know that reality may be more challenging because the device must be placed exactly on the charger. Xiaomi has a multi-coil charger that can charge multiple devices and can tolerate their positioning on the charger. How does it work? [Charger Lab] Disassembled one and found 19 coils and a lot of thermal management stuffed into the device.
The first part of the post is a brief consumer review of the device, looking at its size and features. But the second part is when the lid comes off. The graphite heat shield looks like something accidentally spilled, but we are sure that it is. The coil is tightly packed in three layers. We have to doubt the interaction between them, and we assume that only some of them are active at any given time. The disassembly revealed many components, and even pulled out the data sheets of many components, but did not really involve the theory of operation.
Nevertheless, from an internal point of view, this is an unusual device. It is impressive to see so much power and thermal management in such a small package. We want to know that we haven't seen more wireless charging in our do-it-yourself projects. Of course, we did see some. Not to mention grafting the charging receiver to an existing mobile phone.
Even the product name on the box is "Multi-coil wireless fast charging board".
This is a very complicated design. The PCB inspection is thorough enough to give you an idea of its function, but I can't believe they only measured the input power and not the actual charging rate. So much thermal management indicates that there is a significant power loss.
Very beautiful dismantling, very beautiful photos and chip identification data sheet.
I still prefer cables, and then throw the phone into the trash on the table.
I am usually a wired person, but for devices that may charge and turn off charging frequently or must be very waterproof, a proper wireless charging solution does make sense to me and can be very efficient in terms of energy transfer.
But this is not the case-the efficiency must be terrible, all the other coils appear in a correctly positioned way, and the deeper coils are further away from the target. What you want is a good registration indicator-visually means that you put things in the right place, or a better design is to gather the equipment in the right place, hiding in the thinnest you can manage A coil behind the skin.
Unless there is a current loop, the "blocking" coil does nothing. My guess is that the charger can make those who resonate best with the mobile phone antenna, because the bane of near-field power transmission is alignment.
My brother has an induction stove, which can heat anywhere and the only place where you put down the pot to a certain extent. This seems to be a looping coil to find which has the largest power consumption, and then use that. (This is based on moving things on it while it is running.)
Even if the coil is open in this way, it will do something-because it will generate some induced current and related losses.
I wonder if they can use overlapping non-optimal coils in a similar way to phased array beam control, so they are actually part of the power transmission...I don’t know in this rather complicated situation what happens.
This is a reply to smolesofbikes: try to hold a coil with 2 anti-parallel LEDs (or bridge rectifier and 1 LED) and resistors near the cooktop during cooking...
When the cookware is not present, the "pot detection" can also be "considered" as a low-power pulse source.
Everyone should try them before they all disappear, the design is incorrect, the slightest fault in the fan speed software will cause the entire unit (including the oven) to be completely wrong due to the short circuit of the output transistor. They won't last long, which is too bad, because the pot is actually more efficient when heating the stove! ! ! !
Because if the boiling water is 100 degrees Celsius, then why is the furnace 500 degrees Celsius? It is like a linear 5v regulator with an operating efficiency of 25v == 1/5 = 20%.
Too bad LEDs don't like to operate at 200 degrees Celsius. …
Yes, when I see a lot of thermal management, my first thought is a lot of power loss! Except that people are too lazy to insert, I don't see its appeal! Roughly speaking, there is also the problem of contact failure, which is the only thing I can see that makes this technology useful.
All this kluge design work plus power transmission loss and possibly significant RF interference (if there are a billion in the world, both of which will become real problems), so you don’t have to plug in a smelly USB cable...
How is it mixed? Have you read fine articles? You know that the field strength decreases with the square of the distance, don't you? Have you never needed (send the phone) to repair a worn USB connector?
Please stay tuned for the next episode...
It is basically an air gap transformer, if the gap is zero (and the coils are perfectly aligned and touching each other), the maximum power transmitted may be about 70%. As the distance between the coils increases, the transmission efficiency decreases exponentially. Therefore, if you read between the information on the first link above "Input: 9-20V, 6A Max" and "Total output: 60W Max", it will waste 50% of the power for me. Do we really need to build more than 100% power plants worldwide, because some idiots cannot handle the problem of plugging in cables. What is the next step to replace the power outlet? *Palm*
However, it does not have to be just power transmission-you can also use the coil transmission stage as part of a transformer from high voltage to low voltage. I have not studied the options of commercial brands to see if any of them meet the principle, but if they do, the transformer loss in the air gap becomes less important-because you won’t be able to do so anyway. No lossy power conversion is performed, so it may convert the efficiency from 80-90% to 70% (the numbers are actually arbitrary).
There are some very good reasons for not having to plug in cables-such as waterproof equipment, and equipment for those with visual/motor impairments. You must also realize that the normal wear and tear of loose cables means that they may need to be replaced more than once, which is actually an important energy cost for manufacturing and transportation-a more fixed charging device should mean it can last a long time.
A well-designed SMPS (switching power supply) can have an efficiency of up to 95%!
Let us see what they got: "Input: 100-120V~50/60HZ 1.7A" (~170W ignore power factor) "Output: 5V3A, 9V3A, 11V6A, 20V4.8A" (15W, 66W, 96W)~ 56% efficiency "input: 220-240V~50/60HZ 1.7A" (~374W ignore power factor) "output: 5V3A, 9V3A, 11V6A, 20V6A" (15W, 66W, 120W) ~ 32% efficiency
That was before using their air gap transformers to reach 50% efficiency.
So actually their efficiency on 100V AC is 28% (I didn’t even use 110V AC, 25.7% would be worse) or they get 16% efficiency on 220V AC
I’ve never said that the efficiency is good, but in these cases it may not be as bad as it sounds-I don’t know if this situation applies to any wireless charging, but directly use wall AC power (or at least almost directly put it down for small The power limitation in the coil may) wireless to the other end of the DC rectifier/last stage means that the overall efficiency is not that bad.
Since what you end up doing is actually comparing an almost certain ferrite core with an air core (maybe coupled with a ferrite core) and the same DC rectifier stage-it will still loosen to the cable because It is of course, but it is no different from directly converting alternating current to direct current without feeding direct current to convert it into various alternating currents for transmission, and then back to direct current. In any case, devices such as phone chargers are usually not known for their efficiency. This is the cheapest thing to convert AC power to phone-fed DC power. The company can escape by selling/giving away the device...
As I have already said here, I am mainly a cable TV guy, and they are better. But wireless does have potential benefits and uses.
Depending on the technology, it can be a resonant coil transformer, which solves the efficiency problem by recovering the unused energy in each cycle.
An ordinary transformer simply reverses the magnetic field every cycle and consumes energy to push current through the copper, regardless of whether the other coil picks up anything. The efficiency of the air gap transformer is particularly low, because it requires a lot of current to maintain the field strength at a distance, so the secondary can induce any voltage from it.
The resonant transformer runs a resonant LC resonant circuit on both sides, which oscillates on its own, so there is no need to drive so much current to keep the transformer running. Also at the receiving end, the resonant circuit means that it can keep the voltage rising in a weaker field, because the oscillation can grow over multiple cycles, which further reduces the requirement for high drive current on the primary side. If the distance between the primary and secondary circuits is relatively short, this can actually provide quite high efficiency in the 90% range.
Or in other words, the resonant transformer has a higher Q factor than the conventional inductive charger, which has some active circuit elements connected in series with the transformer with significant ohmic losses, and the actual switching and current reversal are performed every cycle. In the resonant transformer, the oscillating current is generated by itself in the LC resonant circuit, and the switching element simply "complements" it to maintain the ringing, thereby minimizing I^2R loss.
100% increase in power plants? Do you really think that mobile phone charging consumes so much of our power generation?
Yes, it’s not great to have such efficiency, but... if you want to really change something, you can get a lot of benefits elsewhere.
There are currently approximately 5.27 billion ACTIVE mobile phones on the planet. Compared with 7.2 million electric vehicles. If there is no legislation to force manufacturers not to waste energy, both may waste a lot of energy.
There are also talks about making inductive pads for electric cars and trucks. There is a lot of wasted electricity now.
Have you never encountered a port failure on your tablet/phone? This is where I fail the most. This has not been a problem since I switched to wireless charging 90% of the time. In other words, I have no problems adjusting things these days. When I had an LG G3 (big mobile phone and charger are small hockey pucks), I came back, but not recently.
Except for my first phone, every phone I replaced (the screen burned so badly that I couldn't read it anymore) was because the USB port failed and the phone was no longer charging. The current mobile phone LG has a USB connector with 16 surface mount and 5 through-hole pins. The surface mount part is completely surrounded by a large number of 0201 decoupling caps, so when I use a hot air pencil, they start to blow off The board is before the connector reflow. (Of course, use polyimide tape and then polyimide to pull them all down.) I can't use a hot plate because there are temperature sensitive components on both sides of the plate. I think no matter how low the efficiency is, inductive charging will be a big improvement. (And how difficult is it to make a groove in the shape of the phone so that it automatically aligns to the best coupling?)
The irony is that the power port is standardized as USB instead of the traditional barrel jacket. USB connectors are designed for computer peripherals. They were not originally designed for thousands of insertion cycles, even though USB-C is like this now, if you believe they are made this way.
In addition, the port failure on the mobile phone is the manufacturer's choice. The main problem is that the connector peels off from the PCB, because the part is simply soldered on, any degree of twisting and swinging will cause this. Old Nokia had connectors on individual micro-modules, and these modules themselves had a simpler spring-loaded connector to the edge of the PCB, so if you managed to break the connector, it was actually easy to replace. Open the phone, take out the module, and put in a new one.
Yes, they will interfere like hell due to misalignment, and it can't be used as a transformer completely, but more like a loosely coupled inductance circuit. The frequency of harmonics is far more than 30 MHz, and has a certain line length, which is a good broadband noise source.
When a simple USB data cable is sufficient for any brand of mobile phone (except fruit brands), I don't think this complicated wireless charging device is of much use.
If you want to do something peculiar, then use a 3D printer to make a docking station, or just plug the USB cable into the phone, wrap something around it, and then apply some plaster around it and let it dry to make A docking station.
Then I am very grateful that innovation in the world does not depend on you.
I am also tired of not finding suitable consumer products because of the so-called "innovation".
A good docking station with physical contact requires some float on one side or the other (maybe even on both sides), otherwise they will never slide into each other cleanly. Take a look at laptop docking stations, they usually have 3-4 mm clearance in the xy direction (for example something close to 2 mm from the center) and a point in the z direction, with some kind of longer guide pins To help guide them together.
Don't think that you are wrong to think that cables are usually good enough, but the original docking station you suggest will either not work at all or will inevitably put pressure on one or two connectors, leading to faster failures.
If the cable is not plugged in at all, children cannot permanently damage your phone by pulling the wrong plug, tripping over the cable, etc. (they are very creative and accidentally damage things they don’t even use). : Knock the head meme:
The USB port has always been the main killer of my equipment, so it’s great not to have to use it. (This also means that you can actually use the waterproof function too softly when you were on vacation.) We have a USB-pd charger that we sometimes use while holding it for charging, and of course there is also a USB battery, but sitting at any time It's time for the charger to be less susceptible to port damage. It also reduces the wear and tear of the shell-we use huge OtterBox defender shells, and their flaps cover the ports and sometimes wear out.
As for tripping over wires, my bolt cat pulled my $160 original Amazon Echo from the fireplace to the floor (only convenient locations) and smashed it into hundreds of pieces. Since then, I now use magnetic coupling charging cable adapters on everything.
Simply getting rid of the cat will be more convenient and more responsible for the environment. It's also cheaper.
Although I can't blame the cat's wisdom for taking out the Echo.
OK. So my impulse is to say that it is not the cat that poses a danger to the environment, it is obviously the United States. But I will not do that. Oops! So is it the United States or their environment or the environment of everything? But if you just don’t like cats, then just say it so that you don’t pass the “Human Better” test.
It seems normal for cat owners to defend against this and see the conspiracy to hate cats in normal words. This is weird and a bit creepy.
But my statement is simple: cats are destroying things and causing you to buy more finished products, and are spending your direct expenses on care and feeding. Both the disposal and manufacture of goods have environmental costs. The simplest solution is to remove the agent that caused the damage and expense.
These "magnetically coupled charging cable adapters" I guess it is a type that is magnetically fixed together, ie. Rather than a friction fit or snap connection. The contacts are pressed together by a pair of magnets.
This magnetically fixed connector does not have any disadvantages of wireless charging.
To be fair, I hope to see more magnetic contact fair. The downside is how trivial it is for them to disconnect, but sometimes this is the feature, just like the echo kills the cat.
I tried some magnetic cables and they worked quite well, at least for USB 2.0 stuff. There are too many potential conductors in a USB 3 cable, and trying to find a conductor compatible with the device can become a mess.
They also use fairly small pogo pins to fit the space occupied by the cable head, so they are quite delicate, even if you take good care of them, pogo pins may not be rated so many cycles...I didn’t manage I put on one of the 3 I went out, but lost a damaged pogo pin in my laptop bag on my first or second trip-I think it is connected to a fairly powerful magnet, which will The head is stuck on the surface of the bag at the rivets, and the weaving makes them bend... but there is really no way of knowing what managed to enter and destroy them.
It’s some better magnetic cable coupling technology-but I don’t know for those stupid, uncomfortable, craze that has taken over modern portable devices...
I also added magnetic couplers for almost all USB devices that need to be charged/powered, but it is not important for data speed (headphones, mice, Arduino and even phones, because I rarely connect to them via USB). The magnetic "plug" also prevents the USB connector from filling the pocket with cotton.
> When a simple USB data cable is sufficient for any brand of mobile phone, except for fruit brands
Since the launch of the first iPhone in 2007, fruit brand smartphones have been charged via USB. You just have to use the included data cable. Now we have USB-C-even fruit brand laptops can be charged via USB.
No iPhone has used a USB data cable to charge.
The original iPhone uses Apple's proprietary 30-hole dock connector, and newer models use Apple's proprietary lightning cable. None of these proprietary connectors are USB.
Yes, you can get a cable with a USB-C connector on one end, a chip inside to tell your phone that this is a certified cable, and a lightning connector on the other end, but this is definitely not a USB-C cable. Like A-to-lightning, A-to-30pin, etc., USB is standard, but non-standard cables are not.
I have always wanted to make such a charger, but there is no position-independent goal. I'm imagining a physical connector that can... the female side of one end is just the secondary wound in the air, and then the male side will be the primary or maybe just the same ferrite core as the primary. I imagine it as The sealed bicycle light is charged like a column with a diameter of 1 cm and a height of 1 cm. So it’s not small enough for a smartphone, obviously... Although I think it can be miniaturized, I really don’t know what the trade-offs are (transformers are always a journey of discovery for me).
It still requires physical mating in a specific location, but it may be relatively insensitive to direction. It will mechanically enforce its position requirements without having to have tight connectors that are difficult to insert. And, most importantly, it will not be affected by any contact costs-oxidation, stickiness, or entry point. Maybe this is naive to me, but I think it is more effective than a parallel winding with only one common air core, which is a more traditional charger. This is important in my book, because heat is something that kills lipids, and I think the typical design of a thermal (inefficient) coil 1 mm away from the current rechargeable battery is just a thing that cannot be activated at all for me.
The reason I have never even tried it in a bicycle light project is that the standard old micro USB proved to be great. Sometimes you have to replace cables, but jacks are basically indestructible, even if you install them permanently a few inches from your bicycle tires. Combined with the fact that water ingress does not seem to damage my light (the only delicate component is the push button switch, which I also found to be very reliable in this environment), I just don't have any need to try anything different. I think I’m just lucky, but I’ve been building such a light for a few years and have never encountered a problem with a switch or micro USB.
To be fair, wireless charging seems too stupid. And since efficiency decreases with increasing distance between coils, a board like this does add some extra distance to some of its coils. This cannot be for efficiency.
The wireless charger actually provides power efficiency that lacks gloss in exchange for some extra comfort. It is fair for device manufacturers to implement contact-based solutions instead. But it is obviously difficult to determine a standard docking solution. (You can specify that the two outer corners of the "bottom" edge of the phone should be charging terminals, and they should be at least X cm away from the center of the device, and then the charging stand is quite simple to make, especially if the provided voltage meets the standard, you can negotiate through NFC In short, the charging dock has become more or less one of those clip-based mobile phone holders.)
But back to the wireless charger.
To some extent, I personally wouldn't be surprised if it ends up being illegal outside some niches.
However, to be fair, wireless charging may already be illegal in the European Union. (This is the situation in 2009, but it is clearer in the current directive, but as we see below, it is not clear enough, I cannot write "yes" instead of "maybe".)
Since 2019:1782, according to the European Parliament and Council Directive 2009/125/EC, the eco-design requirements for external power supply have been formulated and the Commission Regulation (EC) No 278/2009 (the name of the actual directive that has been entered) has been abolished. )
This directive has minimum requirements for external (mains) power sources. The power supply under load needs to be at least 67% efficient. (If it is less than 49 watts. (If it is less than 1 watt, it is 16%.))
If you build a wireless charging station with an AC inlet and no other output. Then because there is no satisfactory efficiency, this is obviously illegal. (I recommend actually reading the instructions here.) Giving it some other output will only make it more suspicious, and may still be illegal, because one of its modes of operation is not effective enough.
If the wireless charger is not connected to the power source. (The "mains power" in the directive refers to 230 ± 10% volt alternating current 50 Hz from the grid. (Actually, the EU mains power is 230 10 or -6% "coordinated" on paper, in fact it is close enough. That is, All EU countries should not change what they currently use. But back to wireless chargers))
So technically speaking, you don't need to care about this instruction. However, people may still need to comply with it. Because the instruction focuses on the efficiency from the power supply to the "main load".
Anything we add between the main power supply and the main load will cause the efficiency to decrease, and ultimately, the efficiency is not satisfactory. We can argue that a sufficiently long cable on the low-voltage side will reduce efficiency. But we should probably look at the actual operating conditions.
But the directive never defines the meaning of "primary load". Is it the next load in the chain? Or other equipment closer to our chain?
Consider how the directive defines the definition of "mains" power supply, as well as almost all other technical terms that we might question. So why not define what can be considered the main load?
Although this instruction lists a long list of sample loads, non is a device mainly related to powering other devices. (If we technically make exceptions for furnaces and other heaters.)
Except for "battery chargers without power supply function". However, you can put your phone on the wireless charger and still use it for other purposes instead of waiting for charging. Since the wireless charger not only powers the battery, but also powers the entire device, it can be said that the charger provides some power supply functions. However, the wireless charger is usually not powered by a power source, so it is not restricted by the instruction itself.
I think wireless chargers are currently legally suspicious as a whole. Since we don’t know what this directive means for "primary load", we don’t know if the wireless charger is part of our power solution.
If the wireless charger is considered part of the power solution. That is, between the power source and our main load, the wireless charger does affect the overall efficiency. And since there is currently no wireless charger with an efficiency higher than 67%, it cannot be used legally in practice, at least when connected to the main power source. (After all, the directive does not cover non-mains power supplies.)
However, in fact, wireless chargers need to be more efficient, because we also need to consider the efficiency of the power supply and the voltage drop in the actual long cable. (Yes, if our main load is on the other side of it, even the cable is important. The instruction here can just state a simple "100 milliohm cable." And call it a day, because most ordinary cables are There is resistance on or below.)
(Although one might argue that the magnetic field stores energy in it, this technically makes the charger a very short-term UPS, so in addition to instructions. (This is a joke.))
I want to see the graph of electromagnetic field and some closed-form Maxwell electromagnetic field equations. This is certainly much more complicated than the equation of motion of any multi-body celestial body.
https://bilder3.n-tv.de/img/incoming/origs22630906/186279849-w0-h0/imago1003194852h.jpg https://apps-cloud.n-tv.de/img/22631268-16241672120306o /2436/bg -por-ger-4-.jpg https://apps-cloud.n-tv.de/img/22631273-1624167214000/o/2436/2436/bg-por-ger-8-.jpg
You forgot Maxwell's equations.
There is a difference between the electricity that is thrown away and the electricity that is temporarily stored for later recovery. Resistance and reactance.
This is not the case with wireless chargers. A considerable amount of energy is lost through the resistance heating in the primary coil. A considerable part will escape as EM radiation. In short, the drive circuit itself has not been reabsorbed much if it even tries to start like this.
The rule of thumb for inductive loads on power grids does not really apply to this type of equipment.
The famous inventor (and the original wireless power transmission researcher, you may remember) Benjamin Franklin once said (similarly): "Those who give up basic efficiency for temporary convenience, they are not worthy ."
More than ten years ago, my Palm Pre wireless charging was all solved through magnetic alignment. It is fast and should be the future of charging, but it is lost in patent hell.
Magnetic plug guys! They are awesome!
I bought 2 cables and a plug. The plug is always on the phone, one cable is on the head of the bed, and the other is on my desk. Plugging and unplugging is effortless, no power down, no power down. You can buy cables or plugs or kits. And they are very cheap, only a few dollars in your favorite Chinese market.
I even plan to buy some as birthday gifts, which is a cheap thing that can greatly improve your quality of life.
Just saw one of them installed on someone's phone about a week ago-it does seem to be the best choice for this type of gadget-may be more important than wireless charging
"And a lot of thermal management is stuffed into the equipment"
Kind of talk about wireless charging
The irony of wireless charging is that it requires more wires.
In the last few photos, do I see a lot of unreflowed solder paste?
Yes, I also want to know what that trash is!
As for efficiency, why not look at the capacity (in mAh) of the DC power supply and the cell phone battery. Compare it to using a direct USB charging cable?
This measurement may tell you efficiency more directly than the hypothesis presented above...
They said in an article about the charger laboratory. This is the residue of thermal silica gel.
I think it will be easier and cheaper to use a coil with an XY bed to optimize the position of the coil based on the measured power transmission.
Or hang the coil on a spring and align it with a magnet?
Or just magnetic cables/contacts. Just like a Pebble watch. It should also work well on mobile phones. If you want to be fancy, use some robots to plug in the contacts when you throw the phone on the charger.
The whole idea of wireless charging is to be able to put the phone on the charger without having to fiddle with the plug. Wireless charging is just a solution. There can also be a robot that plugs the charger cable into the phone.
It seems that wireless charging is mainly chosen as the solution because it looks fancy.
We want to know that we haven't seen more wireless charging in our do-it-yourself projects.
Well, maybe I should write some of my toys. Most of them are components combined with kapton (I will work on PCB someday), but I have started putting Qi receivers in them so that I can make the case waterproof. I use magnets to help with alignment, so to a large extent I can put the device on the charger and it will align and charge by itself.
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