arduino - PID regulation for very wide temperature range (?190°C)

Question

I'm designing temperature control system based on Peltier elements. And it's needed to work on a very wide temperature range - from below zero to more than 100°C. So there is two work modes - cooling and heating. I've implemented a PID controller, made different gains for two modes. And I can adjust them to go to a specific temperature (e.g. 100° or -5°) from room temperature (25°). But when I want to go e.g. from -5° to 60° it may go into oscillations or conversely grow very slowly. Should I break my large range in smaller subranges? Or maybe different gains depending on difference between current and target temperature (?T)?

Also, I thought to implement auto tune algorithm, but I didn't found anything for the Arduino?

question from:https://stackoverflow.com/questions/65626495/pid-regulation-for-very-wide-temperature-range-%e2%88%86190c

Answer 1

Your system of mass, heater and cooler is subjected to some delays. (imagine you are tuning temperature of the water shower with two water knob, that kind of delay!) And, PID control strategy is not capable to compensate delays. That's why there are oscillations.

One of the best ways to control delayed systems is using the MPC controllers.