Micro-controller adjustabe Buck converter? (for MPPT)

[Tim Wescott]

8051!!?!?!??!!! [0]

I've done PWM with an 8051, and I've done PWM wiht a 68HC11, and
if I ever do PWM again it will be with Motorola, I think.

Speaking of PWM, I'm entertaining fantasies of a battery-operated
MIG welder again, where I'd need a buck regulator that could
regulate current up to about 65A with a source of 24V nom.
of Lead-Acid batteries and a welding arc for a load. Well, there's
no reason to lock into lead-acid, if any other style of battery
would make more sense for an app like this. Highest power density
is the operative word there, I think.

What would it cost to have a real engineer design something like
that?

Thanks,
Rich

stevo wrote:

Hi,

I am designing a MPPT (Maximum Power Point Tracking) device to be used
with a solar panel. In the design I need a high efficiency buck
converter whose output can be controlled by a micro-controller. The
general requirements are:

1. Vin min ~ 12V Vin Max ~ 22V
2. Vout mine ~ 13V Vout Max ~ 18 V
3. At least 0.5A of current
4. Adjustable output (in a way that can be controlled by a uC).

Anyone know of such a device? Do PWM buck converters do this? Most
adjustable buck converters that I have seed require 2 resistors to set
the output voltage. I suppose I could use a digital pot for this, but
that adds a lot of complexity.

Thanks
Stephen

If you're willing to learn the switching regulator theory, consider
getting a microcontroller with some ADC inputs and a PWM output, then
drive the FET straight from that. You'll be putting yourself into a
space where a software fault will let the smoke out of you drive
devices, but it'll be a minimum parts-count system, to be sure!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

[0]

That's not just idle talk. We used an 8051 controlled PWM, and kept
blowing

transistors and traces until the software guy got it right.

BTW, I don't see anything wrong with the digital pot. The advantage there
is

that you can put fixed resistors around it to limit the range.

Tam

Is that an official offer for the group to flood this thread with offers
to work for you? Why not TIG? MIG is (a) tame and (b) needs the damn
wire feed mechanism.

If you're seriously interested check my web page (or the pages of any of
the other contractors on the list). Call if you're interested.