Hi Everyone,
I’m designing a project and wanted to reach out for input. I need to build a device for a lab application that will quite quickly heat and then rapidly cool a small plate. My thought was to use a series of Peltier devices and then use a motor controller to change the polarity to the Peltiers to heat and cool. Does this sounds reasonable? I’ve having a lot of difficult selecting the best controller for this job. The device will be built around a simple Arduino and needs to change temperature from about 20C up to 45C and then back down.
The properties of the Peltiers are below and I was thinking of hooking up 4 or 6 of them in series to cover a plate that’s about 4" by 6".
lmax - 7A
Umax - 15.4V
Qcmax - 62.2W
Tmax - 69C
1.7 Ohm resistance
127 thermocouples
Max Operating Temp: 180°C
Min Operating Temp: -50°C
Thank you so much for any assistance.
Fishbulb
The H-bridge in a motor driver can turn the voltage on, off, or reverse the polarity to a resistive load like a Peltier element but resistive loads behave differently than inductive loads like motors when using a PWM cycle to limit power, so there are some specific things to be careful of. In general, if you were using a motor controller like our High-Power Simple Motor Controller G2 24v19 to control a single Peltier element, you should not use a power supply that is over the maximum rated voltage of the element.
-Nathan
That’s very helpful nathanb. Thanks you a lot. Do you see any issue with wiring the Peltier’s in series as long as the current through them remains well under their listed Amps and the voltage does not exceed their Umax 15.4V? My thought would be to stay very far below these values but just use the additional elements to get more even heating and cooling.
Thank you again. I will go ahead and buy the motor controller. Cheers,
FB
We do not have a lot of experience with Peltier elements like that. Looking briefly at a few datasheets, it seems like their electrical properties (current consumption at different voltages) are dependent on the temperature difference between the hot and cold side. It seems like that thermal behavior would exaggerate smaller unit to unit variations if a string of these is wired in series, but without some kind of quantitative model or some testing, it is difficult to say how well it would work. Having all of the elements on the same heat spreaders would tend to equalize temperature differences, which would help balance the load. In general, it seems like connecting them in parallel (so there is a constant voltage across each element) is more stable, since elements that start to get a little hotter will then draw less current.
-Nathan
