Improving the speed of induction charging

[Lobotomy]

If charging some smaller toy, phone, electric razor, toothbrush or the like with induction charging I assume that the speed (time it takes to charge an empty battery) will depend on

1. the battery to some extent, but for this sake let's omit that
2. the inductive charging it self
3. wall socket outlet power would probably not be a bottleneck.

So if it is safe to assume that the conductive charging is the bottleneck here - how to improve the speed? A battery, provided it can receive the current, would charge faster with a stronger current, right? And the wall socket and transformer would be likely to be able so supply the maximum amount possible?

Inductive charger takes in electricity from the wall socket 220V (probably transformed down to something) and then it has a primary coil and a secondary coil, and probably some other components. Not sure if there is a magnet in there or not?

What components and parameters in the inductive charger do I need to change in order for the battery to charge faster? Things i could possibly change would be
1. the wire it self - how about a thicker copper wire with less resistance? perhaps other material?
2. the number of winds in the coil primary and/or secondary coil
3. stronger magnet?
4. other components? perhaps oscillator - AC with higher frequency can be transmitted more effectively?

Any ideas. And please don't overcomplicate it, it's a simplified example concerning the basics of how this works.

 

[Baluncore]

Any ideas. And please don't overcomplicate it, it's a simplified example concerning the basics of how this works.

The charger has an oscillator and a transmitter coil, like but less powerful than an induction cooktop. The device being charged has a receiver coil, followed by an AC to DC rectifier, and a battery charge regulator.

There is a reason why it is designed the way it is, with just enough to do the job, at the minimum cost. If you change anyone detail of the functioning system, you will then need to upgrade other parts of the system to handle the increased power. Failure to do a complete analysis and redesign will result in a loss of reliability.

There is no simple way to increase the rate of battery charging.

 

[Lobotomy]

The charger has an oscillator and a transmitter coil, like but less powerful than an induction cooktop. The device being charged has a receiver coil, followed by an AC to DC rectifier, and a battery charge regulator.

There is a reason why it is designed the way it is, with just enough to do the job, at the minimum cost. If you change anyone detail of the functioning system, you will then need to upgrade other parts of the system to handle the increased power. Failure to do a complete analysis and redesign will result in a loss of reliability.

There is no simple way to increase the rate of battery charging.

it's a theoretical example. think of it as for educational purpose in a high school physics book or something. I am not redesigning my phone charger =)

So youre saying to increase the charging speed - assuming the battery can manage you'd need to change ALL these parts:
1. have a "better" oscillator - or whatever better means?
2. have a "better" transmittor coil - whatever better means?
3. have a better reciever coil - whatever better means?
4. have a better AC to DC rectifier- whatever better means?
5. have a better battery charge regulator - whatever better means?

If we assume (yes this is not reality) that 1, 4 and 5 above can manage the increase. What do you need to do with the transmittor and reciever coil to make them "better"?

 

[Baluncore]

Yes.

If you change the oscillator to increase the power, or raise the frequency, you will have to also redesign the transmitter coil.

If more power is transmitted, the receiver coil and rectifier will need to handle the extra power, or switch faster at the higher frequency.

The battery charger part will need to be reprogrammed, so as to charge the fixed voltage battery at a higher current, and the battery will need to survive the faster charge.

Why use the word "better" if no one knows what it means ?

 

[Lobotomy]

Yes.

If you change the oscillator to increase the power, or raise the frequency, you will have to also redesign the transmitter coil.

If more power is transmitted, the receiver coil and rectifier will need to handle the extra power, or switch faster at the higher frequency.

The battery charger part will need to be reprogrammed, so as to charge the fixed voltage battery at a higher current, and the battery will need to survive the faster charge.

Why use the word "better" if no one knows what it means ?

the goal is for the battery to charge faster. faster= better. But this must translate into technical specification changes of parts.

So let omit all parts except for the reciever and transmitter coil. We assume all other parts can manage the increase (or has already been improved to do so)

The remaining question is - what do you need to do with the transmittor coil and reciever coil to increase the charging speed. How would they need to be redesigned to handle the extra power?

 

[Baluncore]

The coils form an inefficient transformer. Make the coils greater in diameter but keep them the same distance apart. That will increase the coupling and make it possible for more energy to cross the gap.

The transmitter coil is effectively part of the oscillator circuit, mess with the coil and you mess with the oscillator.

 

[Lobotomy]

The coils form an inefficient transformer. Make the coils greater in diameter but keep them the same distance apart. That will increase the coupling and make it possible for more energy to cross the gap.

The transmitter coil is effectively part of the oscillator circuit, mess with the coil and you mess with the oscillator.

ok thanks so greater in diameter implies increasing the number of windings in the coil i guess?

 

[Baluncore]

ok thanks so greater in diameter implies increasing the number of windings in the coil i guess?

No. If you do that the inductance of the coil will increase, so the frequency will be lower. You need to maintain the same inductance of the coil, while increasing the outside diameter, by adjusting the number of turns and the spacing.
http://www.circuits.dk/calculator_flat_spiral_coil_inductor.htm

 

[anorlunda]

Any ideas. And please don't overcomplicate it, it's a simplified example concerning the basics of how this works.

Designing a battery charger is inherently complicated. It would take an experienced engineer days to do that. There is no uncomplicated answer.

 

[Lobotomy]

Designing a battery charger is inherently complicated. It would take an experienced engineer days to do that. There is no uncomplicated answer.

Nobody is designing a battery charger. Its a question regarding some of the most important basic princples on how it works. If you google principles on inductive charging you will find videos explaining things in a asimple and basic way, that of course is not sufficient explanation on how everything works for a design engineer to actually construct a charger. Its a difference.

 

[anorlunda]

Nobody is designing a battery charger.

Yes you are. Details like wire size and number of turns are design details.

how to improve the speed?

Improve relative to what? That has no meaning except to compare different designs.