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1 V and 100 Amp.!!! from 24 V DC source..

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mananshah93

New Member
Hi to all!!!
I need to generate 1V and 100 Amp. for heating application from 24V dc source....how can I generate it??

Can high frequency transformer(around 40Khz) helps??
Do anyone know this kind of transformer??
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hi to all!!!
I need to generate 1V and 100 Amp. for heating application from 24V dc source....how can I generate it??

Can high frequency transformer(around 40Khz) helps??
Yes, you need a switch-mode power supply.

Do anyone know this kind of transformer??
You wind it yourself, or have one custom wound.

Bear in mind the secondary winding needs to be VERY thick.
 

mananshah93

New Member
You wind it yourself, or have one custom wound.

Bear in mind the secondary winding needs to be VERY thick.
ya, I know it is difficult to get, but you mentioned for thick winding (I guess for high currrent), do you think size can be compact like this shown in the figure if it is made???


30.0× 27.0× 25.5 mm
 

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Nigel Goodwin

Super Moderator
Most Helpful Member
ya, I know it is difficult to get, but you mentioned for thick winding (I guess for high currrent), do you think size can be compact like this shown in the figure if it is made???
I doubt there's room on such a small core for 100A wire, but if the core is rated at over 100W you may be able to use multiple thin wires in parallel to make a high current secondary, this is common practice anyway, due to the difficulty of winding thick wires. Another common method is to use copper ribbon, rather than wire.

You might consider looking at an old in-car high power amplifier, these have switch-mode supplies in them, but it really depends on how many windings are used on the primary, it's generally not very many.

You might have a look at this page, which gives you plenty of info about it.

Switchmode Power Supply For Car Audio
 

Hero999

Banned
What do you need 1V at 100A for?

This seems like a very unusually low voltage.

I can't see it being very efficient, perhaps 50% at best; the problem is resistive losses on the secondary side, you'll loose 10% efficiency for every 1mΩ.

Use a push-pull configuration and you need synchronous rectification on the secondary side; think of many low Ron MOSFETs in parallel.
 

mananshah93

New Member
What do you need 1V at 100A for?

This seems like a very unusually low voltage.

I can't see it being very efficient, perhaps 50% at best; the problem is resistive losses on the secondary side, you'll loose 10% efficiency for every 1mÙ..


[]

I need this for heating application in which kanthal plate is used as a heating plate,, and moreover my senior has told me that it is better to have 1V , 100Amp.. Actually , even I don't the reason yet...

QUOTE=Hero999;773627]Use a push-pull configuration and you need synchronous rectification on the secondary side; think of many low Ron MOSFETs in parallel.[/QUOTE]

Can you give me some more clarification...how to get this current when I do have source of 24V, 5 Amp...using MOSFET??
 

Hero999

Banned
If your supply is limited to 5A then you have a problem because I doubt you'll be able to get 83.33% efficiency at such a low voltage out.
 

marcbarker

New Member
Don't make it so complicated!!, life's too short!

Get yourself an 'instant heat' gun soldering iron, use the transformer out of it

And a 24 V input Inverter
 
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Hero999

Banned
Isn't the output of the heat gun more likely to be AC than DC?
 

mananshah93

New Member
If your supply is limited to 5A then you have a problem because I doubt you'll be able to get 83.33% efficiency at such a low voltage out.
Anyway...I will certainly try if you suggest your way of doing even on 83.33% efficiency...

I can move the source to little bit higher if required...

Thanks to all ...
specially to marcbaker...I think your suggestion would not fit in my project as it is too space consuming.. and I want this application to fit in my instrument...
 

marcbarker

New Member
Isn't the output of the heat gun more likely to be AC than DC?
Of course it will! :) According to OP, this is a "Heating Application", not a 1 V DC power supply!

Seriously though... WHY does it have to be DC ??

Don't bother with voltage regulation, make it primary-side regulated. A very simple push-pull self-oscillating transformer, with flattened 'capillary' copper tubing 2-turn secondary. If the heater's always going to be connected it's better. Just have a fuse or something for protection.
 
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tcmtech

Banned
Most Helpful Member
You guys are over complicating things.
Just use a group of Ni Cad or NiMh cells in parallel.
Under load they will pull down to around 1.05 volts and can easily source 10 -15 amps per cell with out overheating.

Strip a cordless drill battery pack and rearrange the cells to work as a 1.2 volt high current source.
 

mananshah93

New Member
You guys are over complicating things.
Just use a group of Ni Cad or NiMh cells in parallel.
Under load they will pull down to around 1.05 volts and can easily source 10 -15 amps per cell with out overheating.

Strip a cordless drill battery pack and rearrange the cells to work as a 1.2 volt high current source.
In that way, how many cells I have to put in parallel...because space is a concern for me , because I have to put this application into the instrument...

and what about the recharching, I think this would be also a issue because it will be used for years...
 

Mr RB

Well-Known Member
Just what is this weird secret device and just what does it have to heat? What is your power supply and what size does the whole device have to fit into??
 

mananshah93

New Member
Just what is this weird secret device and just what does it have to heat? What is your power supply and what size does the whole device have to fit into??
Heating Element: Kanthal plate
power supply: 24V 5-6Amp.
Device: It is a device which is used to heat the samples(sand samples) to particular temp. for particular time , and record the data.. it's scientific instrument , used in research ...

We are trying to replace bulky AC transformer with high frequency DC if possible with small size,,,
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Heating Element: Kanthal plate
power supply: 24V 5-6Amp.
Device: It is a device which is used to heat the samples(sand samples) to particular temp. for particular time , and record the data.. it's scientific instrument , used in research ...

We are trying to replace bulky AC transformer with high frequency DC if possible with small size,,,
Normal low frequency transformers may be large, but they are VERY reliable and efficient, I would advise sticking with what you've got.
 

Hero999

Banned
Here's a simple self oscillating push-pull inverter circuit.

If you wind T1 with the correct turns ratio, you can covert 24VDC to 1VAC squarewave which should power the heater with no problem.

I'd recommend using a grossly oversized core for T1, try 200W, just to make it easy to wind thick wire round. I also recommend using copper strip or many thinner copper wires in parallel. I'd be tempted to try desolder braid covered in a conformal coating (before winding) as an insulating material.
 

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mneary

New Member
Modern CPUs use voltages and currents in this neighborhood. The last one I took apart used 1.1V 75A. It had a bunch of MOSFET pairs driving a bunch of little inductors. They were all sitting next to the CPU fan so I don't guess how efficient they were.

I guess my main point is that 100A can come from 5 supplies contributing 20A each and it becomes a lot simpler. If the load never changes and you don't need tight regulation, you might be able to set the duty cycle (4%?) and forget it. To control current ripple on 24V, you should rotate among drivers rather than dump them all at once.
 
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