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TEC PWM controllers

post #1 of 46
Thread Starter 
These aren't your grandad's PWM fan modules. Some of them might draw 50 Amps @12 or 24V. That said, What exactly should a TEC PWM controller look like? I've seen a few threads on here and most of the members decided to etch their own boards to make them or use linear bench supplies (which will never be small enough to fit inside your case. You can find electric Motor PWM controllers on ebay or amazon for a few bucks. Is there a huge difference in the application that a motor PWM controller/driver would be inadmissable as a TEC driver? The only stumbling block I've seen is most of them are based on a potentiometer for their input control and have no feedback/signals.

Anyone want to take a stab or share their experience with PWM TEC control?
post #2 of 46
http://www.ebay.com.au/itm/TEC-controller-for-Peltier-modules-with-PID-7-25V-max-20A-cooling-mode-/231704893134?hash=item35f2b016ce:g:fJQAAOSwiLdWA-wf

I have 2 of these, they are fantastic units. Can set your temp via the pot and the controller will keep it as close as it can to that set temp via PWM, mine stays very steady at the set temp. It only uses one mosfet though and is only good for 20 amps, you will also need a heatsink to screw onto the mosfet if using more than 13 amps, just buy a TO220 heatsink, they include some thermal pads to isolate the mosfet from the heatsink. You will also need to buy a small sealed bead type 10k NTC Thermistor with wires for the controller to sense the temperature, this will need to be fitted into a hole drilled in the cold plate.

Mine work extremely well but unfortunately 20 amps wasn't enough for my 19940 TEC at startup at 12v, it would pull about 18 amps once running but the controller wouldn't allow it to start when first turned on because of the startup amps when TEC is at room temp being more than 20 amps. I haven't investigated how to modify it to allow more amps or tried to bypass the controller at startup. I believe you can use a very large thermistor in line with the load before the controller to limit the current at startup but I'm not sure if it will work well because it will need to resist current for about 5 seconds before the TEC drops to about a 20-30*c delta and reduces its current below the 20a, not sure if the thermistor is able to do that.
post #3 of 46
http://www.thermomart.com/digital-automatic-temperature-control-instruments?product_id=251

this is the best pre made controller that I have ever seen for controlling TEC's, it is a 30A model.
post #4 of 46
Thread Starter 
Wow, that is a great answer. Thank you!


If you could, please expand on your problem. If it doesn't come on when the dT is its lowest (ambient) vs (ambient), how does it come on at all?


I'm making a chiller with (current build) 8 (HP-199-1.4-.8) 40mm TEC's in a straight thru chiller, very similar (but larger/longer) to Naekuh's Chiller that Martin built. (theirs ended up being too small and too under powered such that even though it kinda worked it did not run at the COP everyone hoped for) These max out at like 11 amps, so without a better idea I'll probably just run 8 PWM controllers and tweak them to get a good balance as the water chills across the plate. The other option I have is to wire all 8 in parallel and drive them with a bench supply which I understand is more efficient to the tune of a few degrees/amp but nothing to write home about. I'm just bothered that I can't fit it all into a box and actually write a piece of software that does some math for me and can do things like the one you found can do like "HOLD" or above dew point...etc.

They also make very large PWM controllers but I'd need something like 60 or 80 amps at least to run all 8 in parallel, and I've only seen motor controllers that large..not sure if there is some subtle difference in the PWM signals that would make it unsuitable.
post #5 of 46
Thread Starter 
surprisingly, I have never found thermomart before, I'll give it a browse. I like the thermostats I was hoping I could use 1 or 2 of the cold loop and 1 or 2 or the hot loop, maybe I can break up my parrallel chain and run 2 or 3 per controller.
post #6 of 46
well if you are making a water chiller there are a few people here at OCN that have already done so I myself am also making a water chiller that I have almost completed, but OCaddict has one that is functional, and puck has made water chillers for his direct die TEC setup. have a browse through all of there build logs. as I have found all of them to be educational builds, that have given me a better understanding of how they work.

http://www.overclock.net/t/1390376/peltier-tec-hybrid-water-cooling
http://www.overclock.net/t/1473171/triple-tecs-double-chiller-direct-die-cascade-sure-why-not
http://www.overclock.net/t/1584867/tec-vacuum-chamber-build-log
post #7 of 46
Thread Starter 
Ive browsed the vacuum one before...I'm afraid I don't get the theory of operation. Are they hoping the rarified air is colder or something? I work with high vacuum for a living in the semiconductor industry and...less air usually means more heat because you're taking away an entire mechanism for heat loss. The reason lower pressure air at altitude is colder in the atmosphere is from the adiabatic lapse rate and black body radiation of the earth.... unless of course the vacuum is there for some other reason.

the other two I'll pull up. Thanks for the info.
post #8 of 46
Quote:
Originally Posted by Alea iacta est View Post

Ive browsed the vacuum one before...I'm afraid I don't get the theory of operation. Are they hoping the rarified air is colder or something? I work with high vacuum for a living in the semiconductor industry and...less air usually means more heat because you're taking away an entire mechanism for heat loss. The reason lower pressure air at altitude is colder in the atmosphere is from the adiabatic lapse rate and black body radiation of the earth.... unless of course the vacuum is there for some other reason.

the other two I'll pull up. Thanks for the info.

it is being used for some other reason.
the idea has been updated from a simple vacuum chamber, to a gas exchange, I am still using a vacuum pump to vacuum down the ice chest, and to dry the inside of the ice chest, then I will be replacing all of the air inside the ice chest with pure nitrogen. so, this way I will have a very dry environment for the PC components to function in.
the idea is that if I do not have any moisture inside the ice chest, as I run cold water through the water blocks, I will not have any condensation forming on the water blocks, or any of the other PC components.
Edited by toolmaker03 - 6/22/16 at 1:30pm
post #9 of 46
Thread Starter 
ah...moisture control... yeah, that just might work. would also be an interesting case. I'd a bunch of desiccant packets as well. Water vapor is tricky/inefficient to pump out with a vane pump. can take hours.
post #10 of 46
Quote:
Originally Posted by Alea iacta est View Post

ah...moisture control... yeah, that just might work. would also be an interesting case. I'd a bunch of desiccant packets as well. Water vapor is tricky/inefficient to pump out with a vane pump. can take hours.
yea, and the way I am doing it, it will take me about 7 to 10 days, but I have a humidity gage in the ice chest, and a camera on that. so, that I can monitoring the progress during the process.
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