021-DRF Rev B
DRC User Manual
12
Copyright © Enovation Controls – 2018
DRF Valve Controller
PID Algorithm
The controller uses a digital, velocity PID algorithm as shown:
O(t) = O(t-1) + P*(e(t)-e(t-1)) + I*T*e(t) + D/T*(e(t) + e(t-2) – 2*e(t-1))
Where:
O = output
P = proportional gain term
I = integral gain term
D = derivative gain term
e(t) = error at time t
T = PID loop time
Setup Procedure
1. Select the operating frequency.
2. Set the Minimum and Maximum Outputs according to the valve specs.
3. Set the Dither Frequency according to the valve specs. Higher dither frequencies can improve frequency
response.
4.
Start with Proportional only to achieve a stable system.
5.
Add Integral.
6.
Add
Derivative to improve system response and/or stability.