PID Controller Constraints

Hi all,

I have implemented a PID temperature controller (based on Voltage control) into my model but I am having one issue with it when I change the setpoint temperature. I have the setpoint temperature change as a function of time and after a few seconds of ramping up I have it drop about 30 degs (simulate cooling) and then my PID algorithm explodes bc of the error term. I was wondering if theres an easy way to make my model use the PID controller for ramp up but then when I want it to cool down just turn have voltage = 0. I have tried using a piecewise function that defines an interval for using V_ctrl and then an interval that V = 0 but my model will not solve.

Any advice?

Thanks
Alex