I want to control peltier element's temperature with a PWM driven bipolar DC motor controller to be able to switch between heating and cooling and also control the level of it. The peltier element is 12V/8.5A. I also have 12.5A DC power adapter.
I want to buy a motor controller (like this 13A controller) in order to simplify the project as much as possible. This particular controller can be driven by 20kHz PWM.
I was thinking about a following circuit:
in1 and in2 would be connected to outputs of a controller. out1 and out2 would be connected to peltier.
Using 1mH inductors and 470uF gives 232Hz rolloff frequency which is 86 times smaller than 20kHz.
I have a few questions:
1) Does this circuit make sense and is it enough for my situation?
2) I found 1mH 10A inductors, but I'm not sure if I should take into account anything else regarding L and C proportions and this particular circuit
3) Do I have to look for anything specific in capacitor or will any 470uF capacitor be fine? Is bipolar capacitor required?
Best Answer
To a first approximation you should be fine. As long as the inductors have decent frequency response, so you don't get much in the way of current spikes, the capacitor will be OK, and does not need to be a low-ESR type. But a better cap, one specified for use in switching applications, would be good insurance.
But hey, the worst that can happen is the cap blows up. Just put a paper cup over it. These things don't send shrapnel flying when they fail.