Rockwell Automation 20C PowerFlex 700H Drives Programming - Manual (Page 93)

Rockwell Automation Publication 20C-PM001F-EN-P - March 2012 93
Application Notes Appendix B
Process PI The internal PI function of the PowerFlex 700H provides closed loop process
control with proportional and integral control action. The function is designed
for use in applications that require simple control of a process without external
control devices. The PI function allows the microprocessor of the drive to follow
a single process control loop.
The PI function reads a process variable input to the drive and compares it to a
desired setpoint stored in the drive. The algorithm will then adjust the output of
the PI regulator, changing drive output frequency to try and make the process
variable equal the setpoint.
It can operate as trim mode by summing the PI loop output with a master speed
reference.
Or, it can operate as control mode by supplying the entire speed reference. This
method is identified as “exclusive mode”
+
+
+
+
z
-1
*
*
PI Fbk
PI Error PI Output
PI Ref
PI Cmd
Linear
Ramp
-
+
-
Linear Ramp
& S-Curve
Spd Ramp
0
+
+
Zclamped
In Limit
PI XS Error
abs
PI_Config
.Exclusive
Current Limit
or Volt Limit
Spd Cmd
*(PI Ref Sel)
*(PI Fbk Sel)
PI Kp
PI Ki
PI Neg Limit
PI Pos Limit
PI_Status
.Hold
Spd Ref
&
PI_Config
.RampCmd
PI_Status
.Enabled
PI_Config
.Invert
PI_Config
.Sqrt
0
PI_Config
.Torq Trim
PI_Config
.SpdReg
PI_Status
.Enabled PI_Config
.ZeroClamp
PI ExcessErr
PI_Config
.PreloadCmd
Preload Value
PI_Status
.Enabled
Spd Cmd
+32K
0
-32K
0
+32K
-32K
Spd Cmd
to A (below)
A
Torq Ref A
Torq Ref B
0
+800
0
-800
0
+800
-800
+
+
+
+
Torq Cmd Vector Control Option
(currently not available for
PowerFlex 700H drives)