0-100 amp continuous current adjustment

Thread Starter

edsaldana

Joined Feb 17, 2012
3
I need to adjust DC current to a resistive load (heater) from 0 -100 amps.
The adjustment needs to be done with a potentiometer and not by PWM.
The source is 48 volts DC.

I was thinking in usng a IGBT, but can't find any reference or sample circuit for this aplication.
Does anybody have any idea how to start?

Thanks!
 

jimkeith

Joined Oct 26, 2011
540
What you need is a buck regulator.
The input to the inductor will be pwm--the output will be DC.
Obtaining a suitable inductor will be more of a problem than the IGBT.
A swinging or saturable reactor may be required to keep the current from becoming discontinuous at low settings.
 

bountyhunter

Joined Sep 7, 2009
2,512
I need to adjust DC current to a resistive load (heater) from 0 -100 amps.
The adjustment needs to be done with a potentiometer and not by PWM.
The source is 48 volts DC.
!
How about a pot that controls the pulse width? A switcher changing the PW is really the only feasible way to do this.
 

crutschow

Joined Mar 14, 2008
23,506
You do not want to use any linear type of control since the power dissipation of the regular could be upwards of 2500W.

PWM (a switching regulator) is the best way to do it. If you just want the current to be adjustable and it doesn't have to be extremely stable with time and temperature, then a simple PWM controller and driver (with a inductor filter if necessary) should suffice.
 

studiot

Joined Nov 9, 2007
4,998
Hello edsaldana and welcome to All About Circuits.
100 amps at 48 volts DC?

A small old fashioned welder might operate at these levels. Try a machine supplier for the controller from one. It should do your job.
But be sure to house it in a well ventilated cabinet for cooling.
 
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Thread Starter

edsaldana

Joined Feb 17, 2012
3
The resistance is only .5 ohms.
What about using a high current Darlington in series with the load and controlling the current by adjusting the base voltage?
Would be too inefficient?

Thanks a lot for all your comments!
 

kubeek

Joined Sep 20, 2005
5,623
Let´s see, say you set 50A to flow through the load. That way, the voltage on the load is 25V, and the voltage drop on the pass transistor is 23V. The power dissipated by the pass transistor is 50A*23V=1150W. I have no idea how you plan to get rid of such heat, even if you had a large bank of transistors that would survive such power.
 

bertus

Joined Apr 5, 2008
20,102
Hello,

Our company makes powersupplies for electromagnets.
There is a 2.7 kW version, that uses water cooling for the powersupply.
It has a transistorbank with about 40 transistors that are mounted on a thick plate with pipes going between the transistors for the water cooling.

Bertus
 

Thread Starter

edsaldana

Joined Feb 17, 2012
3
Thanks Kubeek, so I guess the best option is to use a PWM. Do you think the VLA507 will work? I´m planning to order few of those to play around and see how it works. I will use some 200 amp IGBTs I have with me.


Let´s see, say you set 50A to flow through the load. That way, the voltage on the load is 25V, and the voltage drop on the pass transistor is 23V. The power dissipated by the pass transistor is 50A*23V=1150W. I have no idea how you plan to get rid of such heat, even if you had a large bank of transistors that would survive such power.
 
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