Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 70)

70 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
Permanent Magnet Control
Permanent magnet motor control is selected by setting parameter 485 [Motor
Ctrl Mode] = 2 “Pmag Motor”. Permanent magnet motor control requires a Hi-
Resolution Stegmann encoder, Heidenhain encoder, or compatible resolver
feedback on the motor. Refer to the
PowerFlex 700S AC Drive Phase II Control
Frames 1…6 Installation Instructions, publication 20D-IN024 , for a list of
compatible Hi-Resolution Stegmann encoders and resolvers. Refer to the
Heidenhain Feedback Option Card for PowerFlex 700S Phase II Drives Installation
Instructions, publication
20D-IN017 , for a list of compatible Heidenhain
encoders.
Motor data and an autotune is required for correct operation in this mode. Refer
to
Autotune on page 19 for details on the autotune. Refer to “PowerFlex 700S
Permanent Magnet Motor Specifications” in the PowerFlex 700S AC Drive Phase
II Control - Programming Manual, publication 20D-PM001 , for a list of
compatible Allen-Bradley permanent magnet motors and motor data.
Volts/Hertz Control - v2.003 and later
Volts/Hertz control is used in fan, pump, or multi-motor applications. Volts/
Hertz operation creates a fixed relationship between output voltage and output
frequency.
Configuration:
Volts/Hertz control is selected by setting parameter 485 [Motor Ctrl Mode] = 3
“V/Hz”. Volts/Hertz allows a wide variety of patterns using linear segments. The
default configuration is a straight line from zero to rated voltage and frequency.
This is the same volts/hertz ratio that the motor would see if it were started across
the line. As seen in the diagram below, the volts/hertz ratio can be changed to
provide increased torque performance when required. The shaping takes place by
programming five distinct points on the curve:
1. Parameter 527 [Start/Acc Boost] is used to create additional torque for
breakaway from zero speed and acceleration of heavy loads at lower speeds.
2. Parameter 528 [Run Boost] is used to create additional running torque at
low speeds. The value is typically less than the required acceleration
torque. The drive will lower the boost voltage to this level when running at
low speeds (not accelerating). This reduces excess motor heating that
could be caused if the higher starting acceleration boost level were used.
3. Parameters 529 [Break Voltage] and 530 [Break Frequency] are used to
increase the slope of the lower portion of the Volts/Hertz curve, providing
additional torque.