Electrical – How to regulate 2x130W peltier modules

peltierpwm

I built a small fermentation chamber (cooling box) based on the peltier modules. I know this is not very optimal way as peltiers are not very efficient, but I had my reasons for choosing this way.

Basicaly I was satisfied – it worked decently. I used 2 pieces of TEC-12706 of which each has:

Qmax ~57W,

Imax 6.4A

and Vmax 16.4V.

I used an old ATX PSU which can deliver 18A max and supplied peltiers with 12V. I regulated the temperature of the box with simple arduino based regulation (just ON/OFF via 2 relays). All worked, but I would need a bit of more cooling power. So I ordered 2 pieces of TEC-12715 of which each has:

Qmax 136W,

Imax 15A,

Vmax 15.4V.

What I am trying to achieve now is having better regulation and not just on/off one as I read this is not very good for the peltier modules.

I read quite a nice "answer".
It explains nicely how to create PWM based regulation for the peltier module, but it counts with the max current of ~6 amps. Is it possible to achieve similar pwm regulation circuit but for my setup which would either regulate 2 peltiers separately (2 circuits, each with max ~15A) or both peltiers (1 circuit with max ~30A)? I am wondering if I could modify the parts parameters of the circuit described in the link above to match my max current or if any other modification (adding MOSFETs, coils, diodes) will do the job. Or should I consider completely different solution?

Any suggestions are welcome.

Best Answer

You can do them both in parallel on one circuit. You just need a large (40A) MOSFET or IGBT. IN this case, MOSFET would be far better, as you can just use an opto-isolator working from the Arduino 5V PWM to the supply voltage of the MOSFETs. You could also use multiple MOSFETs in parallel to achieve the same thing, though you may need a greater turn on current. You could also try cooling the MOSFETs fom the Peltier modules, which would use more power, but keep your MOSFETs nice and chilly. If you do not cool them with the Peltiers, make sure the MOSFETs have a large heatsink.