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cheap 200A AC to DC power supply?

Discussion in 'Electronic Design' started by [email protected], Nov 18, 2006.

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  1. Guest

    I want to power 10 thermoelectric heat pumps at once from wall power.
    (120VAC 60Hz). Ripple is somewhat important for these, but precise
    voltage and current regulation is not. Each heat pump draws 17A at full
    power, plus I need some extra current for fans, pumps, etc.. The heat
    pumps need about 17V at full power. So I need an AC to DC power supply
    which takes 120VAC 60Hz and outputs 17V at up to 200A. Could someone
    point me in the right direction here? It needs to cost less than $200.
    Ripple hurts these heat pumps but if its very slow I dont think it will
    matter, even if its a couple volts. Current can vary up to say an amp.
     
  2. John  Larkin

    John Larkin Guest

    That's under 6 cents per watt, about a fourth the going rate for a
    cheap power supply.

    What's the application? It's going to dump a lot of heat somewhere.

    John
     
  3. Have you calculated the coefficient of performance of 10 thermoelectric
    heat pumps? 0.15 or so is typical with liquid cooled heatsinks. Much
    less otherwise.

    These are generally TOTALLY USELESS above the one watt level.

    Because the temperature RISE above their heatsink over ambient will
    GREATLY EXCEED their temperature drop across the module.

    See http://tinaja.com/glib/hack68.pdf for a detailed analysis.

    Would a vortex cooler work instead?

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  4. For what purpose?
     
  5. jasen

    jasen Guest

    that's a 3.4KW dc powersupply, why would you want to power that from 120V
    something like that typically gets a 240V or three phase supply,

    if you need active cooling a mechanical heat pump may perform better.
    probably cost less too.
     
  6. Tony

    Tony Guest

    If you can insulate the Peltier elements, it would generally be easier
    to provide 170VDC at 17A. If the insulation is REALLY good, you could
    just rectify and filter the 120VAC, or preferably work up a PFC front
    end to provide both regulation and an input current waveform that
    doesn't trip out every breaker you connect it to .... or else rethink
    the project or the budget.

    Tony (remove the "_" to reply by email)
     
  7. Arlet

    Arlet Guest

    The filter needs to be pretty good, otherwise the quickly fluctuating
    temperatures cause mechanical stresses which severly reduce the
    lifespan of the Peltier elements.
     
  8. Fred Bartoli

    Fred Bartoli Guest

    Arlet a écrit :
    That's bollocks. You'll have to have a huge LF ripple to kill your TECs.
    Any decently (read not completly screwed) designed PWM supply will give
    you as long a lifespan as a DC battery.
     
  9. Arlet

    Arlet Guest

    That's what I mean. You'll need a real supply, not just a rectifier and
    a few big caps.
     

  10. Can you put the pumps in series?
    If so rectify 120V AC gives you 169.7 V DC, 10 x 17V pumps in series at
    17A total, riplle depends on the cap size.
    4 20A 400V diodes, one huge electrolytic.

    If you cannot put the pumps in series you better use separate power supplies.
    If you can, modify some PC power supplies, so these give 17V, 10A (170VA).
    (put 12V in series with the 5V).
    That will be a cheap solution, PC power with 12V > 17A can be found for
    less then 50$ each, discount for 10 ;-)


    But your data is confusing, at one point you sat 17A, then 10A.
    So check again what you have.
     
  11. Fred Bartoli

    Fred Bartoli Guest

    Arlet a écrit :
    Even that will do unless you have a so small cap that the ripple is more
    than 5-10%.
    The pb associated with ripple are:
    - loss of cooling efficiency
    - if your ripple is too low in frequency WRT thermal inertia, like when
    you're thermal cycling your TEC with a ON/OFF thermostat then you may
    reduce its life.
     
  12. Nope. Ripple is even worst, because the ripple troughs HEAT much more
    than the ripple peaks COOL.

    Your useless COP then becomes an outright joke.

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     

  13. --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  14. The point remains that all he will end up with is a giant HEATER.
    A bonfire would be a lot faster and cheaper.

    Thermoelectrics are utterly useless above a very few watts.

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  15. A co-worker was using one of those in car coolers as a small fridge, off a
    12 V auto battery charger. It wasn't cooling much. I added a large
    electrolytic (souvenired from an old printer) and it started to freeze up.
    We ran it on the 6V setting after that.
     
  16. Fred Bartoli

    Fred Bartoli Guest

    Don Lancaster a écrit :
    Sure that's a lot of heat and inefficient is the keyword that stick to
    TECs. But I don't know if it's useless or not; this just depends on the
    application.
     
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