High Country Tek MVP-F Series - Manual (Page 13)

021-MVP-F Rev A MVP-F User Manual 13
Copyright © High Country Tek, Inc. – 2013
MVP-F
Closed-loop Controller
PID Algorithm
The PID algorithm is a digital, velocity style PID 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 = error at time t
T = PID loop time.
Setup Procedure
The following steps are recommended when commissioning an MVP-F controller:
1. Set the min, max outputs and dither frequency according to the valve specification. Closed loop systems often
require a higher dither frequency for better performance.
2. Set the min and max command as desired for the system.
3. Place the controller in Mode 3 – open loop.
4. Apply a command signal equal to the Minimum Command setting.
5. Set the Minimum Feedback to the value it reads at Minimum Command. Increase the Minimum Feedback to suit
the application if a higher minimum result (pressure or flow) is desired,
6. Apply a command signal equal to the Maximum Command setting.
7. Set the Maximum Feedback to the value it reads at Maximum Command. Decrease the Maximum Feedback to
suit the application if a lower minimum result (pressure or flow) is desired,
8. Place the controller in Mode 1 – normal.
9. Cycle the command through full range to verify desired operation.