Process Pi Loop; Process Pi Reference And Feedback; Process Pi Regulator - Rockwell Automation Allen-Bradley PowerFlex 700S Reference Manual

Process PI Loop

+
PI Reference 181
PI Feedback 182
PI Lpass Filt BW
Logic Command
The drive has a process PI loop that can be used to trim speed, torque, or other
functions.
Logic Status
155 1
(Running)
Logic Command
151 12
(PI Trim En)
183 PI Error
-
Filter
LPass
186
184
PI Prop Gain
ki
s
I Gain
151 14
(PI Trim Hold)
15
(PI Trim Rst)
PI Integ Time 187
PI Preload 185
PI Integ HLim
PI Integ LLim

Process PI Reference and Feedback

The process PI reference and feedback signals are the values set in parameters 181
[PI Reference] and 182 [PI Feedback], respectively. [PI Reference] could be a set
value or linked to a variable parameter such as an analog input. Typically [PI
Feedback] is linked to an analog input value received from a process line
transducer.
The process PI reference and feedback values are compared and an error signal is
created. This error signal is sent to a low pass filter. The filter bandwidth is set by
parameter 184 [PI Lpass Filt BW] in radians/second. The output of the filter is
sent to the process PI regulator.

Process PI Regulator

Parameter 185 [PI Preload] presets the process time. When the PI output is
enabled, the integral term of the process regulator will be preset to start
parameter 180 [PI Output] at the value set in [PI Preload].
Parameter 187 [PI Integ Time] is the integral term for the regulator. It is in units
of 1/seconds. For example, when the [PI Integ Time] is 2, the integrator output
equals 1 per unit in 1 second for 1 per unit error. 1 per unit means 100%.
Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Logic Ctrl State
(ProcsTrim En)
&
157 31
Control Options
153 23
(PITrim EnOut)
kp +
+
P Gain
PI High Limit
PI Lower Limit
190 PI Integ Output
Limit
188
189
Detailed Drive Operation
OR
0
0
PI Output
1
Limit
191
192
Chapter 1
Typically
180
Linked to P22
117