Digitally Controlled DC power supply

hi
i wish to make dc power supply of rating 0-40V, 6A. And want to
control it digitally thru any uController in step of 1V ...that is, i
should be able to set voltage digitally. i 've been working uCon low
power electronics but never tried with such high voltage & power.

plz suggest me any circuit...or any concept

Ankur

 

"Tried and True": Use an 8-bit DAC to command a voltage to an
adjustable power supply. Whether you use the latest resonant-mode
synchronous-rectifying off-line switcher or a '723 and a bunch of
2N3055's is up to you. You will be able to get 0.2V steps (or 0.157V,
if that really floats your boat).

"Get Comments from Genome": Use a microprocessor with a PWM output and
an ADC input as a switched-supply controller; proceed as above. If you
use one of the new fancy DSP motor controllers you can even have
cycle-by-cycle overcurrent protection. You will have difficulty getting
your bandwidth as high as is possible with the "tried and true" method,
but you'll be able to do all sorts of wacky things in the loop if you
feel like it.

 

Subject: Digitally Controlled DC power supply

For a simple linear 40V 6A regulator, you might want to look at the National
Semiconductor data sheet for the LM317HV, particularly the apps circuit on page
8 for current boost. Also, if you look at the various current control and slow
turn-on app circuits, you'll notice that they all have one thing in common --
they are replacing the voltage control potentiometer with a current-sinking
voltage source. Curious -- if you've got a 50VDC V(in) to the regulator, you
can probably use that to power a high voltage op amp which can act as the
current sinking voltage source. To get 0 - 40VDC, you'll need negative1.2V to
positive 38.8VDC output from the op amp.

You also might want to take a look at the current limiting setup for the apps
circuit on p. 8. If you've got a linear with 6 amps and a differential V(in) -
V(out) of 50V, you are going to need a massive heat sink with some serious
fans.

You know, even something that simple is going to be kind of expensive, unless
you've got the mother of all boneyards for junk transformers, caps, heat sinks,
fans and rectifiers. Not to mention all the other stuff you're going to need -
semis, enclosures, meter for output voltage/current display, 5-way binding
posts, &c. You might just want to get a voltage-programmable power supply used
off ebay - you'd probably pay a lot less than components alone, and you'll get
better reliability, too. I'd look at something like a used HP 6266B, which
will give you 0 to 40V at 5 Amps. You can program it from an external voltage
or current source (or resistance source, with opt. 002). Programming speed
isn't too fast, but it is sufficient for most ATE apps.

Good luck
Chris
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