Anyone know how to do wireless power transfer at 24 volts and be able to slow stop and speed up a motor at 30 watt max?


maybe modify one of these:

Thanks

 

Anyone know how to do wireless power transfer at 24 volts and be able to slow stop and speed up a motor at 30 watt max?


maybe modify one of these:

Thanks

Nice pictures!

But no idea of their specifications. Do you have a link to them?

 

https://www.ebay.com/itm/Wireless-C...=2322704059151485576aaa8a4dc490aeda1f4c0642d4

 

there is a couple different ones online wondering if i can modify one?

• Input Voltage Transmitter: 12VDC
• Output Voltage Receiver: 5VDC (regulated)
• Output Current Receiver: 400-500mA
• Distance between Transmitter and Receiver: 1-10mm
• Dimesions: 21x9x2.2mm (Tranmitter), 27x5x2mm (Receiver)
• Coil Dimensions: Radius 30mm, Height 0.85mm
• Coil Inductance: 10µH
• Coil Isolated: yes

 

Without another source of power, my answer is that you can’t with these modules.

First, you need 24V; these only transmit 5V of power. Just using that for an estimate, the efficiency is around 40%. Thus, to get 24V out, you’ll need 57V input.

Secondly, you want 30W. These modules only provide 2.5W of power. You’re more than 10x off.

You’ll be a lot better off starting from scratch.

 

You could use 15 of them in 5S3P to get 25V at 37.5 W, followed by a buck converter.

Why do you want wireless?

Bob

 

Without another source of power, my answer is that you can’t with these modules.

First, you need 24V; these only transmit 5V of power. Just using that for an estimate, the efficiency is around 40%. Thus, to get 24V out, you’ll need 57V input.

Secondly, you want 30W. These modules only provide 2.5W of power. You’re more than 10x off.

You’ll be a lot better off starting from scratch.

Yeah wouldn't mind starting from scratch just not sure what I really need!


thanks

 

You could use 15 of them in 5S3P to get 25V at 37.5 W, followed by a buck converter.

Why do you want wireless?

Bob

its going to go trough thin plastic cant have any wires on the other side.

 

Good luck then.

Bob

 

Good luck then.

Bob

Yeah I know


thanks

 

here is an idea not sure what size transistor and resistor for a 24 volt voltage or even higher.

 

here is an idea not sure what size transistor and resistor for a 24 volt voltage or even higher.

 

Just for a reality check, let’s do some rough calculations. The blue LED needs <20mA and drops about 3.5V

The video uses a 9VDC battery to get that 3.5V. Again, about 40% efficient (calculated by dividing 3.5 by 9). To get 24V, you’d have to input 60VDC!

There is no resistor value or transistor that will get you 24V and that high a wattage with this circuit.

I won’t go in to the current calculations, because I think the previous results are instructional.

I also have doubts as to whether the device in the video is real. Some reality check calculations are the source of my suspicions. But I must be wrong, because everything on the Internet is true!

 

The video uses a 9VDC battery to get that 3.5V. Again, about 40% efficient (calculated by dividing 3.5 by 9).

You cannot calculate the efficiency just using voltage. You must compare the power on both sides.

Bob

 

Note that the quoted transferred voltage/curent values are for the condition where the two coils are only a few mm apart. The energy transfer drops off rapidly with coil separation.

 

Ok, I get it... I was incorrect in my presentation, but not in my point!

How does that information apply in this project? Given that an estimate of output power is 0.07W, in the example circuit, with an input of 9V @3.3A (if that’s real) and a power of 29.7W, what’s the real efficiency! (Not the projected efficiency for illustrative purposes)

Using your input and recalculating my example, I get an efficiency of 0.24%. So to get 30W out, I get that you need 124W input. So tell me, what combinations of voltage and current do you need to get 124W?

So, you have two variables and one result.

If your input voltage is 5V, then you need to supply about 25A. That’s a lot...

If your input voltage is 12V, then you need to supply more than 10A. Still a lot!

If you were to supply 120V, you’d need to supply an Amp of current.

Or looking at it the other way, if you supplied 500mA of current, you’d need to supply 248v of input voltage?

Does everyone see a problem here?

A better solution is to transfer a smaller amount of current and voltage, much less than 30W. Then, use the lower voltage and input to a driver at the higher power level.

Simply, it is impractical to attempt to directly wirelessly transfer 24VDC at 30W. Instead, transfer a signal that drives the higher power requirement.

 

On the other, hand, have a look at this:

Wireless charger for EVs

7.2KW charging power. I don't find an efficiency number.

Bob