2 ms·

I wish we could get some kind of writeup or interview from the RF engineers who worked on Airpower. Overlapping charging coils have been dreamed of pretty much

I wish we could get some kind of writeup or interview from the RF engineers who worked on Airpower. Overlapping charging coils have been dreamed of pretty much since the origin of induction charging but there must be tons and tons of issues we can't even think of. I'd love to hear their stories.

cogman10 8y ago
I wonder how you could do it without seeing some pretty big losses. Wireless charging is already pretty lossy, Dynamic coils though? I mean, I guess you could do it mechanically, but that would still result in less than ideal coils and a noisy device. If you did it through transistors, somehow, then you'd end up with a lot of loss at each transistor. Too few and you don't make a good field. Too many and the losses would be really high. The cost would be crazy as well. For the transistor approach, I don't know, maybe a big silicon wafer? Maybe just a load of transistors and wires. Who knows.
- kdot 8y ago
  One thing about wireless charging is the gap created by phone cases, what does a case do to charging efficiency?
  - PascLeRasc 8y ago
    In practice Qi chargers have just one operating power, either "within range" or "not within range", so whether you have a case or not won't affect charging rate, but in theory RF power does scale with 1/distance². So you could argue that Qi standards engineers did have to limit our usable charging power because they knew cases would be used.
- PascLeRasc 8y ago
  There could be a Qi 2 standard that calls for many tiny coils instead of one big one, and pass much smaller amounts of current in parallel that way. Then you could cover the back of the phone with them and be able to place it anywhere on the mat.
tarikjn 8y ago
How about another layer before passing current into the shaped coils? 1. some sort of liquid crystal layer (transistor based), where all the coils are pre-drawn, only allowing layer 2 to conduct when low current goes through layer 1 2. once the coils are formed, pass actual current through the layer 2

cogman10 8y ago

I wonder how you could do it without seeing some pretty big losses. Wireless charging is already pretty lossy, Dynamic coils though? I mean, I guess you could do it mechanically, but that would still result in less than ideal coils and a noisy device. If you did it through transistors, somehow, then you'd end up with a lot of loss at each transistor. Too few and you don't make a good field. Too many and the losses would be really high. The cost would be crazy as well. For the transistor approach, I don't know, maybe a big silicon wafer? Maybe just a load of transistors and wires. Who knows.

kdot 8y ago
One thing about wireless charging is the gap created by phone cases, what does a case do to charging efficiency?
- PascLeRasc 8y ago
  In practice Qi chargers have just one operating power, either "within range" or "not within range", so whether you have a case or not won't affect charging rate, but in theory RF power does scale with 1/distance². So you could argue that Qi standards engineers did have to limit our usable charging power because they knew cases would be used.
PascLeRasc 8y ago
There could be a Qi 2 standard that calls for many tiny coils instead of one big one, and pass much smaller amounts of current in parallel that way. Then you could cover the back of the phone with them and be able to place it anywhere on the mat.

tarikjn 8y ago

How about another layer before passing current into the shaped coils? 1. some sort of liquid crystal layer (transistor based), where all the coils are pre-drawn, only allowing layer 2 to conduct when low current goes through layer 1 2. once the coils are formed, pass actual current through the layer 2