Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 118)

118 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
The output of the integrator is limited by parameters 188 [PI Integ HLim] and
189 [PI Integ LLim]. [PI Integ HLim] is in per unit and has a range from 0…8. A
value of 1 for [PI Integ HLim] can represent base motor speed, rated motor
torque, or 100% of some external function.
The output of the integrator after the integrator limits can be viewed in
parameter 190 [PI Integ Output].
Parameter 186 [PI Prop Gain] sets the proportional gain of the regulator. For
example, when [PI Prop Gain] is 2, the output of the proportional block will
equal 2 per unit in 1 second for a 1 per unit error.
The output of the integrator, parameter 190 [PI Integ Output], and the output of
the proportional block are summed together.
Process PI Limits
To prevent the regulator output from exceeding a range, an upper and lower limit
can be programmed. Parameter 191 [PI High Limit] sets the high limit for the
[PI Output] signal. [PI High Limit] is in per unit and has a range from 0…8. A
value of 1 for [PI High Limit] can represent base motor speed, rated motor
torque, or 100% of some external function.
Process PI Output
At this point of the process PI loop, some conditions must be met in order to turn
on the PI output (otherwise the PI output is 0).
The PI output can be turned on in one of two ways:
1. Parameter 151 [Logic Command], bit 12 “PI Trim En” is turned on (= 1)
and the drive is running. The running state is indicated by parameter 155
[Logic Status], bit 1 “Active” = 1. When both of these conditions are true,
parameter 157 [Logic Ctrl State], bit 31 “ProcsTrim En” will be on (=1).
2. Parameter 153 [Control Options], bit 23 “PITrim EnOut” is turned on
(=1).
Now the PI output is used to trim speed, torque, or some external loop.
To trim the speed loop, link parameter 21 [Speed Trim 1] or parameter 23 [Speed
Trim 3] to parameter 180 [PI Output].
To trim the torque loop, link parameter 115 [Torque Trim] to parameter 180 [PI
Output].
To trim some other loop, link the desired parameter to [PI Output]. For example,
to use analog output 1 as a trim signal to other equipment, link parameter 833
[Anlg Out1 Real] to [PI Output].