Peltier ramp up / down time

Thread Starter

sheepdog

Joined Jan 26, 2009
12
Hi i have a project that on occasions needs the peltier to ramp down and then ramp up (not instantly) using pwm The time factor for the ramping period is not critical over a period of 10 minutes is no problem. Has anybody an idea of a period i could use to prevent temperature change shock to the peltier, for example would dropping 1 duty cycle every 1 minute be detrimental to the peltier.
Many thanks for any thoughts on this
 

OBW0549

Joined Mar 2, 2015
3,014
I'm no expert on Peltier devices, but from what I've read my understanding is you do NOT want to drive them from a PWM signal because it makes them extremely inefficient. The PWM signal should be filtered instead, so that the Peltier device receives a variable DC signal with little ripple.

That said, I think the answer to your question is, "it depends." Over what temperature range are you ramping up and down? How much thermal mass is being controlled? I imagine that several degrees Celsius per minute would not be a problem, but beyond that I couldn't say.

Linear Technology, Inc. has a pretty good application note on using Peltier coolers; it might contain some good information.
 

Thread Starter

sheepdog

Joined Jan 26, 2009
12
I'm no expert on Peltier devices, but from what I've read my understanding is you do NOT want to drive them from a PWM signal because it makes them extremely inefficient. The PWM signal should be filtered instead, so that the Peltier device receives a variable DC signal with little ripple.

That said, I think the answer to your question is, "it depends." Over what temperature range are you ramping up and down? How much thermal mass is being controlled? I imagine that several degrees Celsius per minute would not be a problem, but beyond that I couldn't say.

Linear Technology, Inc. has a pretty good application note on using Peltier coolers; it might contain some good information.
Thanks for the reply, i am using the pwm to control a buck converter with low ripple, i was just pondering over what time period in ramping down the duty cycle becomes damaging to the peltier. I have read that a manufacturer tested a device between 100 deg c to 30 deg c and then back up again over a 15 minute period and achieved iirc 16 million cycles before performance issues arose
 

OBW0549

Joined Mar 2, 2015
3,014
Thanks for the reply, i am using the pwm to control a buck converter with low ripple, i was just pondering over what time period in ramping down the duty cycle becomes damaging to the peltier. I have read that a manufacturer tested a device between 100 deg c to 30 deg c and then back up again over a 15 minute period and achieved iirc 16 million cycles before performance issues arose
That sounds about right, though I don't know how much faster than that you could go.
 
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