Author Topic: Wireless Phone Charging Circuits  (Read 3085 times)

Offline ZakW

  • High Voltage Technician
  • ***
  • Posts: 180
  • Karma: +6/-0
  • YouTube @QZW_Labs
    • View Profile
Wireless Phone Charging Circuits
« on: September 10, 2020, 09:24:53 PM »
Hello,

Can someone help me understand how these circuits function? I have noticed these multi-coil systems and have a few questions:

- Each coil must be driven by its own driver circuit, right?
     - If so, are they all working at the same frequency?
- Why are the coils overlapped as they are? Does that boost the flux density or range?

https://techcrunch.com/2020/01/03/zens-liberty-wireless-charger-review/





Thanks!
Zak
« Last Edit: September 10, 2020, 09:28:14 PM by ZakW »

Offline Zipdox

  • High Voltage Technician
  • ***
  • Posts: 143
  • Karma: +1/-0
    • View Profile
    • Zipdox
Re: Wireless Phone Charging Circuits
« Reply #1 on: September 10, 2020, 10:02:10 PM »
I assume the coils are driven in phase with eachother, probably each with their own driver yes.

Let's not mention efficiency...

Offline ZakW

  • High Voltage Technician
  • ***
  • Posts: 180
  • Karma: +6/-0
  • YouTube @QZW_Labs
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #2 on: September 10, 2020, 11:14:10 PM »
So as far as power absorption/induction goes, it has to do with how strong of a field the coil(s) is producing and how much the receiving coil(s) is in that field. Far away = less voltage, Closer = high voltage, right?

They mention in the tech crunch article that the charger uses 60W. That's crazy considering a normal phone charger is around 10-20W.

For better efficiency, couldn't you increase the number of coils and reduce their overall output so that when a receiving coil is brought near by its absorbing many weaker signals for more current? Is part of their design to boost the overall field so the charger works through thicker materials (like phone cases and things).

Offline klugesmith

  • High Voltage Senior
  • *****
  • Posts: 688
  • Karma: +22/-0
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #3 on: September 10, 2020, 11:16:01 PM »
We could guess that the coils are arranged in non-overlapping groups.
The coils in a group could all be wired in series or in parallel.
I think it would not help to drive more than one group at the same time, because in many places their fields would cancel.

The pattern could be studied with a small, movable sense coil. Driving a LED?  If the charger won't run without a power receiver/phone, then do the sense coil survey on back side of the charger, while something is getting charged.

60 watts in? ! ! Whatever fraction does not go into battery will go directly to heat.  Could keep a mug of coffee or tea warm while charging the phone.
« Last Edit: September 10, 2020, 11:20:51 PM by klugesmith »

Offline ZakW

  • High Voltage Technician
  • ***
  • Posts: 180
  • Karma: +6/-0
  • YouTube @QZW_Labs
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #4 on: September 10, 2020, 11:38:25 PM »
klugesmith,

From the look of the PCB's on some of them, I would say they appear to all be driven separately. What do you mean the fields would interfere with each other? I am assuming they have studied the pattern they chose. I wonder if I can find any research that was published on the topic.

If I wanted to make a simple circuit with multiple coils just to test different arrangements what would I be looking at for parts? Discrete MOSFET, gate drivers, and something to vary the drive frequency for each coil? Could I feed the same drive signal to each gate drive/MOSFET to cut down on components?

It looks as if they all use litz wire too, is that really necessary?

Offline davekni

  • Executive Board Member
  • *******
  • Posts: 2745
  • Karma: +130/-1
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #5 on: September 10, 2020, 11:46:36 PM »
I expect this is a "smart" charger that senses where the phone or other such device is, then drives a single coil with the closest-to-optimum position.

Frequency is likely high enough where litz wire helps with efficiency.  Especially since overlapping un-driven coils will absorb energy from the one coil selected to be driven.
« Last Edit: September 10, 2020, 11:48:24 PM by davekni »
David Knierim

Offline ZakW

  • High Voltage Technician
  • ***
  • Posts: 180
  • Karma: +6/-0
  • YouTube @QZW_Labs
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #6 on: September 10, 2020, 11:50:49 PM »
I expect this is a "smart" charger that senses where the phone or other such device is, then drives a single coil with the closest-to-optimum position.

Frequency is likely high enough where litz wire helps with efficiency.  Especially since overlapping un-driven coils will absorb energy from the one coil selected to be driven.

I didn't even think of that  :D ! No wonder why they mentioned that "it doesn't matter as much where they device is placed".

In that case, the coils are not laid out like that for any other reason than for coverage of the surface.

Offline Twospoons

  • High Voltage Engineer
  • ****
  • Posts: 221
  • Karma: +6/-0
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #7 on: September 11, 2020, 08:31:28 AM »
I expect this is a "smart" charger that senses where the phone or other such device is, then drives a single coil with the closest-to-optimum position.

Frequency is likely high enough where litz wire helps with efficiency.  Especially since overlapping un-driven coils will absorb energy from the one coil selected to be driven.

You are exactly right. I spent a year working for a company developing this kind of tech.  The coil alignment is critical to getting even vaguely reasonable power transfer and efficiency.   I invented a system whereby the coils were built out of multi-layer pcb instead of litz wire - theres a couple of tricks needed to not melt the pcb.

The efficiency of wireless charging is rather poor compared to a cable though.

Offline Hydron

  • Administrator
  • High Voltage Engineer
  • *****
  • Posts: 487
  • Karma: +25/-0
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #8 on: September 11, 2020, 12:53:15 PM »
The efficiency of wireless charging is rather poor compared to a cable though.
Still, it's handy enough that I would not consider buying a phone without wireless charging these days.
I have a rather early Nokia Qi charger (runs on 12V, 3 coils inside, probably not very efficient) which isn't very fast, but it doesn't need to be when you can just put the phone down on it when going to sleep and wake with an always-full phone (slow charge is probably actually good for battery longevity!).

Offline ZakW

  • High Voltage Technician
  • ***
  • Posts: 180
  • Karma: +6/-0
  • YouTube @QZW_Labs
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #9 on: September 11, 2020, 06:19:42 PM »
Does anyone know of a good starting point for a basic circuit for creating one of these? I have not found very much when searching for a circuit diagram of a wireless charger. It would be cool to see if I could replicate a wireless charger and what efficiencies I could get out of it.

Offline Zipdox

  • High Voltage Technician
  • ***
  • Posts: 143
  • Karma: +1/-0
    • View Profile
    • Zipdox
Re: Wireless Phone Charging Circuits
« Reply #10 on: September 11, 2020, 11:04:51 PM »
Does anyone know of a good starting point for a basic circuit for creating one of these? I have not found very much when searching for a circuit diagram of a wireless charger. It would be cool to see if I could replicate a wireless charger and what efficiencies I could get out of it.
I believe qualcomm has some sort of electrical and communications standard for this. It isn't straightforward at all.

Offline Twospoons

  • High Voltage Engineer
  • ****
  • Posts: 221
  • Karma: +6/-0
    • View Profile
Re: Wireless Phone Charging Circuits
« Reply #11 on: September 12, 2020, 01:02:43 AM »
There are a few companies making chips for the Qi charging standard.

High Voltage Forum

Re: Wireless Phone Charging Circuits
« Reply #11 on: September 12, 2020, 01:02:43 AM »

 


* Recent Topics and Posts

post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
Today at 04:47:35 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
davekni
Today at 03:59:27 AM
post Re: Kaizer VTTC 1
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
March 28, 2024, 09:15:11 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 28, 2024, 01:01:12 PM
post Re: Big Coil Build Log
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 28, 2024, 05:47:34 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
davekni
March 28, 2024, 04:45:07 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 28, 2024, 04:18:27 AM
post Push Pull VTTC
[Vacuum Tube Tesla Coils (VTTC)]
janno288
March 28, 2024, 01:10:08 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 27, 2024, 10:54:52 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 27, 2024, 11:53:42 AM
post Re: OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 05:14:36 AM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:47:48 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:41:59 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 27, 2024, 12:04:34 AM
post Re: Super flat QCW simulation (does this look reasonable?)
[Dual Resonant Solid State Tesla coils (DRSSTC)]
toooldforthis
March 26, 2024, 11:08:14 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 11:07:20 PM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 10:46:29 PM
post OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 26, 2024, 09:03:43 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 08:46:59 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 26, 2024, 05:02:18 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 03:16:03 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 26, 2024, 01:41:49 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 04:48:22 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 26, 2024, 04:16:37 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 26, 2024, 04:16:24 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 26, 2024, 04:13:02 AM
post Re: CM400 Induction Heater
[Electronic Circuits]
davekni
March 26, 2024, 04:00:43 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
davekni
March 26, 2024, 03:19:18 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
March 26, 2024, 01:50:42 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 08:05:02 PM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 25, 2024, 07:41:29 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 06:45:46 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 05:44:25 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 25, 2024, 04:47:17 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 04:27:22 PM
post Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 25, 2024, 03:57:34 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 25, 2024, 02:06:41 PM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 04:43:25 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
davekni
March 25, 2024, 02:39:40 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 12:47:09 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 24, 2024, 07:36:32 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
Alberto
March 24, 2024, 07:27:24 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 24, 2024, 04:25:23 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 10:47:35 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 09:30:21 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 04:34:31 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 03:04:25 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 01:38:34 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 04:20:03 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 23, 2024, 12:54:30 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 23, 2024, 12:05:57 AM
post capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 22, 2024, 11:45:03 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 22, 2024, 11:30:09 PM
post Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 22, 2024, 10:20:35 PM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Benbmw
March 22, 2024, 09:21:13 PM
post Re: What actually kills MOSFETs?
[Beginners]
AstRii
March 22, 2024, 03:37:11 PM
post What actually kills MOSFETs?
[Beginners]
FPS
March 22, 2024, 05:09:20 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 22, 2024, 03:57:54 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 22, 2024, 02:59:25 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 06:31:42 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
rikkitikkitavi
March 21, 2024, 03:08:01 PM
post Re: [WTS] IGBT, Ferrite, Capacitors, Tools, PSU, Industrial components and parts
[Sell / Buy / Trade]
Mads Barnkob
March 21, 2024, 01:37:32 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Alberto
March 21, 2024, 11:42:07 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 21, 2024, 04:09:14 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 02:15:31 AM
post My Homemade Structural Analysis X-Ray Machine
[X-ray]
Luca c.
March 21, 2024, 01:35:40 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 20, 2024, 10:40:00 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Mads Barnkob
March 20, 2024, 08:03:41 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Mads Barnkob
March 20, 2024, 07:51:57 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 20, 2024, 10:39:47 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 20, 2024, 04:09:59 AM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 20, 2024, 01:13:23 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
March 20, 2024, 12:45:16 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 20, 2024, 12:30:30 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 11:12:24 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:47:49 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:44:19 PM
post Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 19, 2024, 06:52:09 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 19, 2024, 05:02:44 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
March 19, 2024, 05:01:41 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 04:31:02 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 03:59:54 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 06:41:39 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 19, 2024, 04:05:49 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 18, 2024, 09:08:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 09:07:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
Twospoons
March 18, 2024, 08:57:06 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
MRMILSTAR
March 18, 2024, 03:51:33 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:59:46 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:33:25 PM
post Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 11:02:12 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Twospoons
March 18, 2024, 02:36:11 AM
post Re: Best forum for vacuum tube amplifiers?
[General Chat]
Mads Barnkob
March 17, 2024, 07:42:55 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:15:14 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 05:05:04 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
davekni
March 17, 2024, 04:50:51 AM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Twospoons
March 17, 2024, 04:45:17 AM
post 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:17:51 AM
post Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Terry
March 17, 2024, 01:29:32 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 17, 2024, 12:33:06 AM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal