TLDR; version: From the summary:
As our setup was still having serious overshoot, a look at the auto-tune results told me by Kd was far too low. I had used the following values:
- Increase Kp to decrease the rise time.
- Increase Kd to reduce the overshoot and settling time.
- Increase Ki to eliminate the steady-state error
Kp = 10.75, Ki = 0.56, and Kd = 51.60
I went in and took Kd back to the default of 114. This is the resultant heating curve from that:
|Kd = 114, target temp 180|
|Kd = 200, target temp 180|
|Kd = 200, Ki = 5.5, temp = 180|
I set the PID_FUNCTIONAL_RANGE to 30 (default was 10) and got the following result:
|PID_FUNCTIONAL_RANGE = 30|