Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 103)

Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013 103
Detail Drive Configuration and Operation Chapter 1
Process PI Reference and Feedback
The reference and feedback signals are the values present in [PI Reference] and
[PI Feedback]. [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 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 [PI
Lpass Filt BW] in radian/second. The output of the filter is sent to the process PI
regulator.
Process PI Regulator
[PI Preload] presets the process time. When the PI Output is enabled, the
integral term of the process regulator will be preset to start [PI Output] at the
value set in [PI Preload].
[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%.
The output of the integrator is limited by [PI Integ Hlim] and [PI Integ Llim].
[PI Integ Hlim] is in per unit and has a range from 0 to 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
[PI Integ Output].
The [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 1per unit error.
The output of the integrator, [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.
[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 to 8. A value of 1 for [PI High Limit] can
represent base motor speed, rated motor torque, or 100% of some external
function.