Question about kd value

[GerhardKreuzer]

Hi,
I looked at your default kd value and read the documents you linked.
Here the findings:
Popular Method (Rule of Thumb)

An easier method of manually determining the P, I and D values is to set the Integral and Derivative terms to off and to set the Proportional Band to a minimum. The resulting oscillation width Xosc and the oscillation period tosc can be used to determine the PID settings shown below.

P = 2.0 * Xosc
I = 1.5 * tosc
D = I / 5

These values result in a slightly over damped response and consequently all values can be reduced slightly to give a more responsive loop.

Your kd value is MUCH higher than ki.

Can you please explain the reasons, thanks a lot.

With best regards

Gerhard

[ScratMan]

Hello, the Kd value strongly depends on the sampling rate of the temperature sensor and inertia of the heating system. The formula is taken from more generic PID docs, they may not fit all applications of PID.