So I'm currently doing a project in college that requires me to use an arduino to control a peltier element. The peltier element will be used only as a cooler. I plan on using a temperature sensor to feed the temperature to the arduino, and for the arduino then adjust the temperature of the peltier.
I have a few questions I'm hoping some people might be able to help me with. The peliter module I'll be using is RH14,14,06 by Laird technologies. The max current it can handle is 6 A, and the max voltage is 1.7 V. I'm planning on having it keep an object at a temperature between 5-10 degrees C.
I understand that the arduino cannot deliver a high enough current to power the module directly and so my first question is how should I interface the peltier module with the arduino?
I've seen in other forums and elsewhere that a MOSFET N channel transistor can be used, or a MOSFET driver, or a thermo-electric controller module (such as MAX1968). I'm just not sure which would be most suitable.
My next question is which type of temperature sensor would be recommended? Again I've seen an RTD - Resistance Temperature Detector used, and also a thermometer device (like DS18B20). I've ruled out using a thermocouple.
Thank you all for any help and advice you may give!
Your choice of temperature sensor will be determined by what is being cooled! Is it air? Is it metal? Is it wood? Plastic? You are also going to need a heat sink and fan for the hot side of the Peltier.
The MAX1968/1969 devices are overkill, since they already provide closed-loop control (no Arduino needed). But if you go this route, use the 1969 (rated at 6A) instead of the 1968 (rated at 3A).
But you can get good results with a power MOSFET like the IRF540. Any temperature sensor would work, and the DS18B20 is a decent choice, considering that libraries for it are widely available for Arduino. And Pail_KD7HB said, you'll need a heatsink for that Peltier module.
The material to be kept at a constant temperature is a small (radius = 12.5mm, thickness = 3mm) stainless steel plate. The Peltier module will be directly applied to the plate.
I've chosen the RTD as the temperature sensor, as it will be possible for me to spark out a hole , a few mm deep in the plate for it to measure from.
I've decided to go with the Arduino and the MOSFET transistor since I need to have some form of software in my project. Since the module will only be cooling, and won't need to be reversed, will I need to use PWM at all to adjust the temperature of the Peltier?
The material to be kept at a constant temperature is a small (radius = 12.5mm, thickness = 3mm) stainless steel plate. The Peltier module will be directly applied to the plate.
I've chosen the RTD as the temperature sensor, as it will be possible for me to spark out a hole , a few mm deep in the plate for it to measure from.
I've decided to go with the Arduino and the MOSFET transistor since I need to have some form of software in my project. Since the module will only be cooling, and won't need to be reversed, will I need to use PWM at all to adjust the temperature of the Peltier?
But, what are you using on the opposite side of the Peltier device to dissipate the heat drawn from the SS plate? And what plans do you have to remove that accumulated heat from the heat sink
As of yet, I've only looked into what heat sinks are available. However the maximum heat that can be expected to be generated in the plate is 0.25W (caused by a machine acting on it), but will more realistically be around 3 milli watts.
I'm not sure if there will be enough heat generated to warrant a heat sink.
If you have the Peltier device at room temperature and power it up, it will be able to burn your fingers within 30 seconds. Trust me, I have tested them while trying to hold them. Don't!
Would I be correct in then saying that the total heat that needs to be dissipated is the heat being removed from the plate and also the heat generated by the Peltier?
Have you any recommendations for what kind of heat sink to use? My first thought would be to use a thermal pad/sheet on the hot side of the peliter connected to a fin heat sink.
Going back to actually driving the peltier, how would you go about controlling the current using the arduino and the mosfet? I've become a bit stuck at this part and can't seem to wrap my head around how i can use the arduino's outputs to adjust the current to the peltier.