Problem driving peltier

Projects General Guidance
1

Hi,

I'm having a big issue trying to power a peltier with a Pololu high power motor driver (this one):

http://www.hobbytronics.co.uk/power-dc-motor-driver-24v-12a

When I set the PWM output of the Arduino to a constant value of PWM, the motor driver don't drive the Peltier with a constant voltage but keeps growing and growing the voltage that feeds the Peltier instead, so I can't get a proper step-response graph (actually it looks like a constant-slope line).

It doesn't matter the PWM value with which I feed the motor driver, it will always keep slowly increasing the voltage the Peltier receives.

What could be failing?

2

Most likely, your code or your wiring is wrong.

3

The increasing voltage may be due to the peltier heating up, resulting in higher resistance.
It depends on your application whether you should worry about that behaviour.

4

I was using a 35V 4A bench power source, I moved to a 40V 10A one and the problem vanished.

It is rather odd because I could drive the peltier without any problems connecting it straight to the previous power source, but everything was ruined when I tried to run it connecting it to the H-Bridge.

As I said, the problem is solved now.

Thank you.