Rockwell Automation 1395 DC Drive, 800-1250 Hp, FRN 5.XX-9.30 - Manual (Page 58)

Chapter 3
Functional Description
3-25
– Field Economy Reference (Parameter 674) specifies the field flux flux
reference to the motor. The flux value specified by this parameter will be
in use when the motor has been stopped for the time specified in the
Field Economy Delay (Parameter 675).
– Minimum Field Regulate Speed (Parameter 686), and velocity Fdbk,
(Parameter 106), are required for Field Weakening. The drive will go
into field weakening when actual speed is greater than base speed, unless
defined otherwise by Minimum Field Regulate Speed (Parameter 686).
This parameter specifies the minimum speed at which field weakening
control and CEMF regulation begins.
The drive will go into field weakening when actual speed is greater than
base speed. The CEMF regulation is always active when flux mode select
(Parameter 627), field weakening (bit 1) is enabled. The output of these
two blocks is applied to a Field Flux Linearization function, whose output
becomes Field Current Reference (Parameter 117). This field current
reference value is summed with the field current feedback value in the
Field PI Control.
Field PI Control (Circle 13)
Field Current Feedback provided from the Feedback Control indicates the
latest field current feedback value and is summed with Field Current
Reference, and applied to the Field Pl Control. Parameter 737 determines
the proportional gain and Parameter 738 determines the integral gain. The
output of the Field PI Control is converted to a time and is sent to the field
SCR bridge.