Peltier Coolers

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Thread Starter

Chris Schene

I am looking for a comprehensive reference on Thermoelectric coolers, a.k.a Peltier devices. I need information such as how one should control them, how to control with maximum efficiency.

I have seen a few applications where PWM is used to control them and wondered, in particular, why they would not just use a DC voltage since with a PWM over 1Khz, the Peltier device will only "see" the DC average of that pulse train anyway.

What about controlling these in an Automotive environment? Any special considerations to think about? Are Automotive environments particularly noisy? Are noise or interference frequencies you would expect to see "floating around" which differ for various manufacturers, countries, regions?
 
Peltier Devices are pretty interesting. DC works best, but the needed currents are high and their pumping can be scaled with the current, hence the typical use of PWM to drive them. I used to work with them in IcePoint Temperature Calibration equipment.

Here is a site with good reading material...
http://www.tetech.com/publications/
 
To control the heat pumping abilities of a peltier device, you need to control the current through it. There are two basic methods;

1) vary the voltage across it. Not very effiecient as power will be lost in the voltage regulating device.

2) PWM - the voltage to the device is "Chopped" at a mark/space ratio that provides the required average level of power. This is the most effecient method - during the "Off" time, there is no current flow and hence no wasted power.

The method you choose all depends upon the degree of control you want and the efficenciey you require.

Audon Electronics offer a range of low-cost self-contained PID peltier device controllers. see http://www.audon.co.uk/controllers.html
 
C

Curt Wuollet

One manufacturer, I believe it's Melcor (or similar) has this information easily available on their website. Quite useful.

Regards

cww
 
M

Michael Griffin

On November 26, 2002 09:26 am, Chris Schene wrote:
<clip>
> I am looking for a comprehensive reference on Thermoelectric coolers,
> a.k.a Peltier devices. I need information such as how one should
> control them, how to control with maximum efficiency.
>
> I have seen a few applications where PWM is used to control them and
> wondered, in particular, why they would not just use a DC voltage
> since with a PWM over 1Khz, the Peltier device will only "see" the DC
> average of that pulse train anyway.

I can't provide you with any information on how to control them, but have you considered that providing a PWM source is likely much cheaper and more efficient than a linear regulator (the alternative I assume you are thinking of)?

> What about controlling these in an Automotive environment? Any special
> considerations to think about? Are Automotive environments
> particularly noisy? Are noise or interference frequencies you would
> expect to see "floating around" which differ for various
> manufacturers, countries, regions?
<clip>

The automotive environment would be concerned about any RFI which your device might emit. I believe the biggest concern is usually avoiding emitting anything which might be audible via the stereo system. Any specifications which might exist would likely come from the auto maker.

Your device must also be very tolerant of large changes in voltage for short or long periods of time. This includes both lower and higher than nominal voltage. You can get large voltage swings as loads cut in and out.


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Michael Griffin
London, Ont. Canada
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im no expert on the subject of peltier cooling devices but...
i have read that using dc for the devices stresses the plates as one heats and enlarges the other cools and shrinks, if this is done many times such as in thermostatic control it can lead to a shortend life of the device.
also because they use high amps they can drain the battery quite quickly, i suppose it depends on what size device you are talking about though.
 
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